diff --git a/client/Android/android_freerdp.c b/client/Android/android_freerdp.c
index 5015d8718..7fb9be4ef 100644
--- a/client/Android/android_freerdp.c
+++ b/client/Android/android_freerdp.c
@@ -57,7 +57,8 @@
 /* Defines the JNI version supported by this library. */
 #define FREERDP_JNI_VERSION "3.0.0-dev"
 
-static void android_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e)
+static void android_OnChannelConnectedEventHandler(void* context,
+                                                   const ChannelConnectedEventArgs* e)
 {
 	rdpSettings* settings;
 	androidContext* afc;
@@ -90,7 +91,7 @@ static void android_OnChannelConnectedEventHandler(void* context, ChannelConnect
 }
 
 static void android_OnChannelDisconnectedEventHandler(void* context,
-                                                      ChannelDisconnectedEventArgs* e)
+                                                      const ChannelDisconnectedEventArgs* e)
 {
 	rdpSettings* settings;
 	androidContext* afc;
diff --git a/client/Mac/MRDPView.m b/client/Mac/MRDPView.m
index bb3aaeb9d..35cebf31c 100644
--- a/client/Mac/MRDPView.m
+++ b/client/Mac/MRDPView.m
@@ -813,7 +813,7 @@ DWORD fixKeyCode(DWORD keyCode, unichar keyChar, enum APPLE_KEYBOARD_TYPE type)
 	mfc->client_width = width;
 }
 
-void mac_OnChannelConnectedEventHandler(void *context, ChannelConnectedEventArgs *e)
+static void mac_OnChannelConnectedEventHandler(void *context, const ChannelConnectedEventArgs *e)
 {
 	mfContext *mfc = (mfContext *)context;
 	rdpSettings *settings = mfc->context.settings;
@@ -835,7 +835,8 @@ void mac_OnChannelConnectedEventHandler(void *context, ChannelConnectedEventArgs
 	}
 }
 
-void mac_OnChannelDisconnectedEventHandler(void *context, ChannelDisconnectedEventArgs *e)
+static void mac_OnChannelDisconnectedEventHandler(void *context,
+                                                  const ChannelDisconnectedEventArgs *e)
 {
 	mfContext *mfc = (mfContext *)context;
 	rdpSettings *settings = mfc->context.settings;
diff --git a/client/Mac/cli/AppDelegate.m b/client/Mac/cli/AppDelegate.m
index e6e625bd0..a4904542f 100644
--- a/client/Mac/cli/AppDelegate.m
+++ b/client/Mac/cli/AppDelegate.m
@@ -13,10 +13,10 @@
 #import <freerdp/client/cmdline.h>
 
 static AppDelegate *_singleDelegate = nil;
-void AppDelegate_ConnectionResultEventHandler(void *context, ConnectionResultEventArgs *e);
-void AppDelegate_ErrorInfoEventHandler(void *ctx, ErrorInfoEventArgs *e);
-void AppDelegate_EmbedWindowEventHandler(void *context, EmbedWindowEventArgs *e);
-void AppDelegate_ResizeWindowEventHandler(void *context, ResizeWindowEventArgs *e);
+void AppDelegate_ConnectionResultEventHandler(void *context, const ConnectionResultEventArgs *e);
+void AppDelegate_ErrorInfoEventHandler(void *ctx, const ErrorInfoEventArgs *e);
+void AppDelegate_EmbedWindowEventHandler(void *context, const EmbedWindowEventArgs *e);
+void AppDelegate_ResizeWindowEventHandler(void *context, const ResizeWindowEventArgs *e);
 void mac_set_view_size(rdpContext *context, MRDPView *view);
 
 @implementation AppDelegate
@@ -197,7 +197,7 @@ void mac_set_view_size(rdpContext *context, MRDPView *view);
  * On connection error, display message and quit application
  ***********************************************************************/
 
-void AppDelegate_ConnectionResultEventHandler(void *ctx, ConnectionResultEventArgs *e)
+void AppDelegate_ConnectionResultEventHandler(void *ctx, const ConnectionResultEventArgs *e)
 {
 	rdpContext *context = (rdpContext *)ctx;
 	NSLog(@"ConnectionResult event result:%d\n", e->result);
@@ -226,7 +226,7 @@ void AppDelegate_ConnectionResultEventHandler(void *ctx, ConnectionResultEventAr
 	}
 }
 
-void AppDelegate_ErrorInfoEventHandler(void *ctx, ErrorInfoEventArgs *e)
+void AppDelegate_ErrorInfoEventHandler(void *ctx, const ErrorInfoEventArgs *e)
 {
 	NSLog(@"ErrorInfo event code:%d\n", e->code);
 
@@ -249,7 +249,7 @@ void AppDelegate_ErrorInfoEventHandler(void *ctx, ErrorInfoEventArgs *e)
 	}
 }
 
-void AppDelegate_EmbedWindowEventHandler(void *ctx, EmbedWindowEventArgs *e)
+void AppDelegate_EmbedWindowEventHandler(void *ctx, const EmbedWindowEventArgs *e)
 {
 	rdpContext *context = (rdpContext *)ctx;
 
@@ -269,7 +269,7 @@ void AppDelegate_EmbedWindowEventHandler(void *ctx, EmbedWindowEventArgs *e)
 	}
 }
 
-void AppDelegate_ResizeWindowEventHandler(void *ctx, ResizeWindowEventArgs *e)
+void AppDelegate_ResizeWindowEventHandler(void *ctx, const ResizeWindowEventArgs *e)
 {
 	rdpContext *context = (rdpContext *)ctx;
 	fprintf(stderr, "ResizeWindowEventHandler: %d %d\n", e->width, e->height);
diff --git a/client/Sample/tf_channels.c b/client/Sample/tf_channels.c
index 71f706624..53a145273 100644
--- a/client/Sample/tf_channels.c
+++ b/client/Sample/tf_channels.c
@@ -73,7 +73,7 @@ static UINT tf_update_surfaces(RdpgfxClientContext* context)
 	return CHANNEL_RC_OK;
 }
 
-void tf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e)
+void tf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e)
 {
 	tfContext* tf = (tfContext*)context;
 
@@ -103,7 +103,7 @@ void tf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs*
 	}
 }
 
-void tf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e)
+void tf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e)
 {
 	tfContext* tf = (tfContext*)context;
 
diff --git a/client/Sample/tf_channels.h b/client/Sample/tf_channels.h
index b1c0b8655..d00a5c2f0 100644
--- a/client/Sample/tf_channels.h
+++ b/client/Sample/tf_channels.h
@@ -27,7 +27,7 @@
 int tf_on_channel_connected(freerdp* instance, const char* name, void* pInterface);
 int tf_on_channel_disconnected(freerdp* instance, const char* name, void* pInterface);
 
-void tf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e);
-void tf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e);
+void tf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e);
+void tf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e);
 
 #endif /* FREERDP_CLIENT_SAMPLE_CHANNELS_H */
diff --git a/client/Wayland/wlf_channels.c b/client/Wayland/wlf_channels.c
index 6df91c0bb..a0b86565e 100644
--- a/client/Wayland/wlf_channels.c
+++ b/client/Wayland/wlf_channels.c
@@ -99,7 +99,7 @@ static void wlf_encomsp_uninit(wlfContext* wlf, EncomspClientContext* encomsp)
 		wlf->encomsp = NULL;
 }
 
-void wlf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e)
+void wlf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e)
 {
 	wlfContext* wlf = (wlfContext*)context;
 
@@ -140,7 +140,7 @@ void wlf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs
 	}
 }
 
-void wlf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e)
+void wlf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e)
 {
 	wlfContext* wlf = (wlfContext*)context;
 
diff --git a/client/Wayland/wlf_channels.h b/client/Wayland/wlf_channels.h
index c56be6a9e..e8760316b 100644
--- a/client/Wayland/wlf_channels.h
+++ b/client/Wayland/wlf_channels.h
@@ -31,7 +31,7 @@
 int wlf_on_channel_connected(freerdp* instance, const char* name, void* pInterface);
 int wlf_on_channel_disconnected(freerdp* instance, const char* name, void* pInterface);
 
-void wlf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e);
-void wlf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e);
+void wlf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e);
+void wlf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e);
 
 #endif /* FREERDP_CLIENT_WAYLAND_CHANNELS_H */
diff --git a/client/Wayland/wlf_disp.c b/client/Wayland/wlf_disp.c
index 51a5f9e31..f06d0040a 100644
--- a/client/Wayland/wlf_disp.c
+++ b/client/Wayland/wlf_disp.c
@@ -165,7 +165,7 @@ static BOOL wlf_disp_check_context(void* context, wlfContext** ppwlc, wlfDispCon
 	return TRUE;
 }
 
-static void wlf_disp_OnActivated(void* context, ActivatedEventArgs* e)
+static void wlf_disp_OnActivated(void* context, const ActivatedEventArgs* e)
 {
 	wlfContext* wlc;
 	wlfDispContext* wlfDisp;
@@ -187,7 +187,7 @@ static void wlf_disp_OnActivated(void* context, ActivatedEventArgs* e)
 	}
 }
 
-static void wlf_disp_OnGraphicsReset(void* context, GraphicsResetEventArgs* e)
+static void wlf_disp_OnGraphicsReset(void* context, const GraphicsResetEventArgs* e)
 {
 	wlfContext* wlc;
 	wlfDispContext* wlfDisp;
diff --git a/client/Windows/wf_channels.c b/client/Windows/wf_channels.c
index f6d29240b..b83d92a90 100644
--- a/client/Windows/wf_channels.c
+++ b/client/Windows/wf_channels.c
@@ -31,7 +31,7 @@
 #include <freerdp/log.h>
 #define TAG CLIENT_TAG("windows")
 
-void wf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e)
+void wf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e)
 {
 	wfContext* wfc = (wfContext*)context;
 	rdpSettings* settings = wfc->context.settings;
@@ -76,7 +76,7 @@ void wf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs*
 	}
 }
 
-void wf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e)
+void wf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e)
 {
 	wfContext* wfc = (wfContext*)context;
 	rdpSettings* settings = wfc->context.settings;
diff --git a/client/Windows/wf_channels.h b/client/Windows/wf_channels.h
index 64a408ac6..867631062 100644
--- a/client/Windows/wf_channels.h
+++ b/client/Windows/wf_channels.h
@@ -20,6 +20,7 @@
 #define FREERDP_CLIENT_WIN_CHANNELS_H
 
 #include <freerdp/freerdp.h>
+#include <freerdp/client.h>
 #include <freerdp/client/channels.h>
 #include <freerdp/client/rdpei.h>
 #include <freerdp/client/rdpgfx.h>
@@ -29,7 +30,7 @@
 
 #include "wf_client.h"
 
-void wf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e);
-void wf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e);
+void wf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e);
+void wf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e);
 
 #endif /* FREERDP_CLIENT_WIN_CHANNELS_H */
diff --git a/client/X11/xf_channels.c b/client/X11/xf_channels.c
index 6253aca6e..b17266636 100644
--- a/client/X11/xf_channels.c
+++ b/client/X11/xf_channels.c
@@ -36,7 +36,7 @@
 #include "xf_disp.h"
 #include "xf_video.h"
 
-void xf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e)
+void xf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e)
 {
 	xfContext* xfc = (xfContext*)context;
 	rdpSettings* settings;
@@ -95,7 +95,7 @@ void xf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs*
 	}
 }
 
-void xf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e)
+void xf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e)
 {
 	xfContext* xfc = (xfContext*)context;
 	rdpSettings* settings;
diff --git a/client/X11/xf_channels.h b/client/X11/xf_channels.h
index c12d823dd..86b00b953 100644
--- a/client/X11/xf_channels.h
+++ b/client/X11/xf_channels.h
@@ -31,7 +31,7 @@
 #include <freerdp/client/geometry.h>
 #include <freerdp/client/video.h>
 
-void xf_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e);
-void xf_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e);
+void xf_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e);
+void xf_OnChannelDisconnectedEventHandler(void* context, const ChannelDisconnectedEventArgs* e);
 
 #endif /* FREERDP_CLIENT_X11_CHANNELS_H */
diff --git a/client/X11/xf_client.c b/client/X11/xf_client.c
index 9100ed463..00792002b 100644
--- a/client/X11/xf_client.c
+++ b/client/X11/xf_client.c
@@ -1766,7 +1766,7 @@ DWORD xf_exit_code_from_disconnect_reason(DWORD reason)
 	return reason;
 }
 
-static void xf_TerminateEventHandler(void* context, TerminateEventArgs* e)
+static void xf_TerminateEventHandler(void* context, const TerminateEventArgs* e)
 {
 	rdpContext* ctx = (rdpContext*)context;
 	WINPR_UNUSED(e);
@@ -1774,7 +1774,7 @@ static void xf_TerminateEventHandler(void* context, TerminateEventArgs* e)
 }
 
 #ifdef WITH_XRENDER
-static void xf_ZoomingChangeEventHandler(void* context, ZoomingChangeEventArgs* e)
+static void xf_ZoomingChangeEventHandler(void* context, const ZoomingChangeEventArgs* e)
 {
 	xfContext* xfc = (xfContext*)context;
 	rdpSettings* settings = xfc->context.settings;
@@ -1798,7 +1798,7 @@ static void xf_ZoomingChangeEventHandler(void* context, ZoomingChangeEventArgs*
 	xf_draw_screen(xfc, 0, 0, settings->DesktopWidth, settings->DesktopHeight);
 }
 
-static void xf_PanningChangeEventHandler(void* context, PanningChangeEventArgs* e)
+static void xf_PanningChangeEventHandler(void* context, const PanningChangeEventArgs* e)
 {
 	xfContext* xfc = (xfContext*)context;
 	rdpSettings* settings = xfc->context.settings;
diff --git a/client/X11/xf_disp.c b/client/X11/xf_disp.c
index 1577b24e2..25fca8777 100644
--- a/client/X11/xf_disp.c
+++ b/client/X11/xf_disp.c
@@ -213,7 +213,7 @@ static void xf_disp_OnActivated(void* context, ActivatedEventArgs* e)
 	}
 }
 
-static void xf_disp_OnGraphicsReset(void* context, GraphicsResetEventArgs* e)
+static void xf_disp_OnGraphicsReset(void* context, const GraphicsResetEventArgs* e)
 {
 	xfContext* xfc;
 	xfDispContext* xfDisp;
@@ -231,7 +231,7 @@ static void xf_disp_OnGraphicsReset(void* context, GraphicsResetEventArgs* e)
 	}
 }
 
-static void xf_disp_OnTimer(void* context, TimerEventArgs* e)
+static void xf_disp_OnTimer(void* context, const TimerEventArgs* e)
 {
 	xfContext* xfc;
 	xfDispContext* xfDisp;
diff --git a/client/iOS/FreeRDP/ios_freerdp.m b/client/iOS/FreeRDP/ios_freerdp.m
index 295d769a8..711880b75 100644
--- a/client/iOS/FreeRDP/ios_freerdp.m
+++ b/client/iOS/FreeRDP/ios_freerdp.m
@@ -28,7 +28,7 @@
 
 #pragma mark Connection helpers
 
-static void ios_OnChannelConnectedEventHandler(void *context, ChannelConnectedEventArgs *e)
+static void ios_OnChannelConnectedEventHandler(void *context, const ChannelConnectedEventArgs *e)
 {
 	rdpSettings *settings;
 	mfContext *afc;
@@ -56,7 +56,8 @@ static void ios_OnChannelConnectedEventHandler(void *context, ChannelConnectedEv
 	}
 }
 
-static void ios_OnChannelDisconnectedEventHandler(void *context, ChannelDisconnectedEventArgs *e)
+static void ios_OnChannelDisconnectedEventHandler(void *context,
+                                                  const ChannelDisconnectedEventArgs *e)
 {
 	rdpSettings *settings;
 	mfContext *afc;
diff --git a/include/freerdp/event.h b/include/freerdp/event.h
index 15623625f..826609e61 100644
--- a/include/freerdp/event.h
+++ b/include/freerdp/event.h
@@ -23,6 +23,8 @@
 #include <freerdp/api.h>
 #include <freerdp/freerdp.h>
 
+#include <winpr/collections.h>
+
 #ifdef __cplusplus
 extern "C"
 {
diff --git a/libfreerdp/core/freerdp.c b/libfreerdp/core/freerdp.c
index 1f44dba7d..04c7e049a 100644
--- a/libfreerdp/core/freerdp.c
+++ b/libfreerdp/core/freerdp.c
@@ -601,14 +601,14 @@ const char* freerdp_get_build_revision(void)
 }
 
 static wEventType FreeRDP_Events[] = {
-	DEFINE_EVENT_ENTRY(WindowStateChange) DEFINE_EVENT_ENTRY(ResizeWindow)
-	    DEFINE_EVENT_ENTRY(LocalResizeWindow) DEFINE_EVENT_ENTRY(EmbedWindow)
-	        DEFINE_EVENT_ENTRY(PanningChange) DEFINE_EVENT_ENTRY(ZoomingChange)
-	            DEFINE_EVENT_ENTRY(ErrorInfo) DEFINE_EVENT_ENTRY(Terminate)
-	                DEFINE_EVENT_ENTRY(ConnectionResult) DEFINE_EVENT_ENTRY(ChannelConnected)
-	                    DEFINE_EVENT_ENTRY(ChannelDisconnected) DEFINE_EVENT_ENTRY(MouseEvent)
-	                        DEFINE_EVENT_ENTRY(Activated) DEFINE_EVENT_ENTRY(Timer)
-	                            DEFINE_EVENT_ENTRY(GraphicsReset)
+	DEFINE_EVENT_ENTRY(WindowStateChange),   DEFINE_EVENT_ENTRY(ResizeWindow),
+	DEFINE_EVENT_ENTRY(LocalResizeWindow),   DEFINE_EVENT_ENTRY(EmbedWindow),
+	DEFINE_EVENT_ENTRY(PanningChange),       DEFINE_EVENT_ENTRY(ZoomingChange),
+	DEFINE_EVENT_ENTRY(ErrorInfo),           DEFINE_EVENT_ENTRY(Terminate),
+	DEFINE_EVENT_ENTRY(ConnectionResult),    DEFINE_EVENT_ENTRY(ChannelConnected),
+	DEFINE_EVENT_ENTRY(ChannelDisconnected), DEFINE_EVENT_ENTRY(MouseEvent),
+	DEFINE_EVENT_ENTRY(Activated),           DEFINE_EVENT_ENTRY(Timer),
+	DEFINE_EVENT_ENTRY(GraphicsReset)
 };
 
 /** Allocator function for a rdp context.
diff --git a/libfreerdp/gdi/video.c b/libfreerdp/gdi/video.c
index ac62d5a94..3384622e5 100644
--- a/libfreerdp/gdi/video.c
+++ b/libfreerdp/gdi/video.c
@@ -147,7 +147,7 @@ void gdi_video_control_uninit(rdpGdi* gdi, VideoClientContext* video)
 	gdi->video = NULL;
 }
 
-static void gdi_video_timer(void* context, TimerEventArgs* timer)
+static void gdi_video_timer(void* context, const TimerEventArgs* timer)
 {
 	rdpContext* ctx = (rdpContext*)context;
 	rdpGdi* gdi;
diff --git a/server/proxy/pf_client.c b/server/proxy/pf_client.c
index 642929a8c..841c98014 100644
--- a/server/proxy/pf_client.c
+++ b/server/proxy/pf_client.c
@@ -69,7 +69,7 @@ static BOOL proxy_server_reactivate(rdpContext* ps, const rdpContext* pc)
 	return TRUE;
 }
 
-static void pf_client_on_error_info(void* ctx, ErrorInfoEventArgs* e)
+static void pf_client_on_error_info(void* ctx, const ErrorInfoEventArgs* e)
 {
 	pClientContext* pc = (pClientContext*)ctx;
 	pServerContext* ps;
@@ -91,7 +91,7 @@ static void pf_client_on_error_info(void* ctx, ErrorInfoEventArgs* e)
 	freerdp_send_error_info(ps->context.rdp);
 }
 
-static void pf_client_on_activated(void* ctx, ActivatedEventArgs* e)
+static void pf_client_on_activated(void* ctx, const ActivatedEventArgs* e)
 {
 	pClientContext* pc = (pClientContext*)ctx;
 	pServerContext* ps;
diff --git a/server/shadow/Win/win_rdp.c b/server/shadow/Win/win_rdp.c
index cf9acddd1..21c37eb6c 100644
--- a/server/shadow/Win/win_rdp.c
+++ b/server/shadow/Win/win_rdp.c
@@ -21,6 +21,7 @@
 #endif
 
 #include <winpr/crt.h>
+#include <winpr/assert.h>
 #include <winpr/print.h>
 #include <freerdp/log.h>
 
@@ -28,22 +29,29 @@
 
 #define TAG SERVER_TAG("shadow.win")
 
-static void shw_OnChannelConnectedEventHandler(void* context, ChannelConnectedEventArgs* e)
+static void shw_OnChannelConnectedEventHandler(void* context, const ChannelConnectedEventArgs* e)
 {
 	shwContext* shw = (shwContext*)context;
+	WINPR_ASSERT(e);
 	WLog_INFO(TAG, "OnChannelConnected: %s", e->name);
 }
 
-static void shw_OnChannelDisconnectedEventHandler(void* context, ChannelDisconnectedEventArgs* e)
+static void shw_OnChannelDisconnectedEventHandler(void* context,
+                                                  const ChannelDisconnectedEventArgs* e)
 {
 	shwContext* shw = (shwContext*)context;
+	WINPR_ASSERT(e);
 	WLog_INFO(TAG, "OnChannelDisconnected: %s", e->name);
 }
 
 static BOOL shw_begin_paint(rdpContext* context)
 {
 	shwContext* shw;
-	rdpGdi* gdi = context->gdi;
+	rdpGdi* gdi;
+
+	WINPR_ASSERT(context);
+	gdi = context->gdi;
+	WINPR_ASSERT(gdi);
 	shw = (shwContext*)context;
 	gdi->primary->hdc->hwnd->invalid->null = TRUE;
 	gdi->primary->hdc->hwnd->ninvalid = 0;
@@ -104,9 +112,10 @@ static int shw_verify_x509_certificate(freerdp* instance, const BYTE* data, size
 	return 1;
 }
 
-static void shw_OnConnectionResultEventHandler(void* context, ConnectionResultEventArgs* e)
+static void shw_OnConnectionResultEventHandler(void* context, const ConnectionResultEventArgs* e)
 {
 	shwContext* shw = (shwContext*)context;
+	WINPR_ASSERT(e);
 	WLog_INFO(TAG, "OnConnectionResult: %d", e->result);
 }
 
diff --git a/winpr/include/winpr/collections.h b/winpr/include/winpr/collections.h
index df14f03a6..c1e76b463 100644
--- a/winpr/include/winpr/collections.h
+++ b/winpr/include/winpr/collections.h
@@ -27,6 +27,7 @@
 
 #include <winpr/winpr.h>
 #include <winpr/wtypes.h>
+#include <winpr/assert.h>
 
 #include <winpr/crt.h>
 #include <winpr/synch.h>
@@ -492,7 +493,7 @@ extern "C"
 	};
 	typedef struct _wEventArgs wEventArgs;
 
-	typedef void (*pEventHandler)(void* context, wEventArgs* e);
+	typedef void (*pEventHandler)(void* context, const wEventArgs* e);
 
 #define MAX_EVENT_HANDLERS 32
 
@@ -505,48 +506,54 @@ extern "C"
 	};
 	typedef struct _wEventType wEventType;
 
-#define EventArgsInit(_event_args, _sender)                  \
-	memset(_event_args, 0, sizeof(*_event_args));            \
-	((wEventArgs*)_event_args)->Size = sizeof(*_event_args); \
-	((wEventArgs*)_event_args)->Sender = _sender
+#define EventArgsInit(_event_args, _sender)       \
+	memset(_event_args, 0, sizeof(*_event_args)); \
+	(_event_args)->e.Size = sizeof(*_event_args); \
+	(_event_args)->e.Sender = _sender
 
-#define DEFINE_EVENT_HANDLER(_name) \
-	typedef void (*p##_name##EventHandler)(void* context, _name##EventArgs* e)
+#define DEFINE_EVENT_HANDLER(name) \
+	typedef void (*p##name##EventHandler)(void* context, const name##EventArgs* e)
 
-#define DEFINE_EVENT_RAISE(_name)                                                           \
-	static INLINE int PubSub_On##_name(wPubSub* pubSub, void* context, _name##EventArgs* e) \
-	{                                                                                       \
-		return PubSub_OnEvent(pubSub, #_name, context, (wEventArgs*)e);                     \
+#define DEFINE_EVENT_RAISE(name)                                                                \
+	static INLINE int PubSub_On##name(wPubSub* pubSub, void* context, const name##EventArgs* e) \
+	{                                                                                           \
+		WINPR_ASSERT(e);                                                                        \
+		return PubSub_OnEvent(pubSub, #name, context, &e->e);                                   \
 	}
 
-#define DEFINE_EVENT_SUBSCRIBE(_name)                                              \
-	static INLINE int PubSub_Subscribe##_name(wPubSub* pubSub,                     \
-	                                          p##_name##EventHandler EventHandler) \
+#define DEFINE_EVENT_SUBSCRIBE(name)                                                              \
+	static INLINE int PubSub_Subscribe##name(wPubSub* pubSub, p##name##EventHandler EventHandler) \
+	{                                                                                             \
+		return PubSub_Subscribe(pubSub, #name, (pEventHandler)EventHandler);                      \
+	}
+
+#define DEFINE_EVENT_UNSUBSCRIBE(name)                                             \
+	static INLINE int PubSub_Unsubscribe##name(wPubSub* pubSub,                    \
+	                                           p##name##EventHandler EventHandler) \
 	{                                                                              \
-		return PubSub_Subscribe(pubSub, #_name, (pEventHandler)EventHandler);      \
+		return PubSub_Unsubscribe(pubSub, #name, (pEventHandler)EventHandler);     \
 	}
 
-#define DEFINE_EVENT_UNSUBSCRIBE(_name)                                              \
-	static INLINE int PubSub_Unsubscribe##_name(wPubSub* pubSub,                     \
-	                                            p##_name##EventHandler EventHandler) \
-	{                                                                                \
-		return PubSub_Unsubscribe(pubSub, #_name, (pEventHandler)EventHandler);      \
-	}
-
-#define DEFINE_EVENT_BEGIN(_name)      \
-	typedef struct _##_name##EventArgs \
-	{                                  \
+#define DEFINE_EVENT_BEGIN(name)      \
+	typedef struct _##name##EventArgs \
+	{                                 \
 		wEventArgs e;
 
-#define DEFINE_EVENT_END(_name)   \
-	}                             \
-	_name##EventArgs;             \
-	DEFINE_EVENT_HANDLER(_name);  \
-	DEFINE_EVENT_RAISE(_name)     \
-	DEFINE_EVENT_SUBSCRIBE(_name) \
-	DEFINE_EVENT_UNSUBSCRIBE(_name)
+#define DEFINE_EVENT_END(name)   \
+	}                            \
+	name##EventArgs;             \
+	DEFINE_EVENT_HANDLER(name);  \
+	DEFINE_EVENT_RAISE(name)     \
+	DEFINE_EVENT_SUBSCRIBE(name) \
+	DEFINE_EVENT_UNSUBSCRIBE(name)
 
-#define DEFINE_EVENT_ENTRY(_name) { #_name, { sizeof(_name##EventArgs), NULL }, 0, { NULL } },
+#define DEFINE_EVENT_ENTRY(name)                     \
+	{                                                \
+#name, { sizeof(name##EventArgs), NULL }, 0, \
+		{                                            \
+			NULL                                     \
+		}                                            \
+	}
 
 	typedef struct _wPubSub wPubSub;
 
@@ -563,7 +570,7 @@ extern "C"
 	                                 pEventHandler EventHandler);
 
 	WINPR_API int PubSub_OnEvent(wPubSub* pubSub, const char* EventName, void* context,
-	                             wEventArgs* e);
+	                             const wEventArgs* e);
 
 	WINPR_API wPubSub* PubSub_New(BOOL synchronized);
 	WINPR_API void PubSub_Free(wPubSub* pubSub);
diff --git a/winpr/libwinpr/utils/collections/PubSub.c b/winpr/libwinpr/utils/collections/PubSub.c
index ba16cf0af..306be1bd7 100644
--- a/winpr/libwinpr/utils/collections/PubSub.c
+++ b/winpr/libwinpr/utils/collections/PubSub.c
@@ -46,6 +46,7 @@ struct _wPubSub
 
 wEventType* PubSub_GetEventTypes(wPubSub* pubSub, size_t* count)
 {
+	WINPR_ASSERT(pubSub);
 	if (count)
 		*count = pubSub->count;
 
@@ -58,12 +59,14 @@ wEventType* PubSub_GetEventTypes(wPubSub* pubSub, size_t* count)
 
 void PubSub_Lock(wPubSub* pubSub)
 {
+	WINPR_ASSERT(pubSub);
 	if (pubSub->synchronized)
 		EnterCriticalSection(&pubSub->lock);
 }
 
 void PubSub_Unlock(wPubSub* pubSub)
 {
+	WINPR_ASSERT(pubSub);
 	if (pubSub->synchronized)
 		LeaveCriticalSection(&pubSub->lock);
 }
@@ -73,6 +76,8 @@ wEventType* PubSub_FindEventType(wPubSub* pubSub, const char* EventName)
 	size_t index;
 	wEventType* event = NULL;
 
+	WINPR_ASSERT(pubSub);
+	WINPR_ASSERT(EventName);
 	for (index = 0; index < pubSub->count; index++)
 	{
 		if (strcmp(pubSub->events[index].EventName, EventName) == 0)
@@ -87,6 +92,8 @@ wEventType* PubSub_FindEventType(wPubSub* pubSub, const char* EventName)
 
 void PubSub_AddEventTypes(wPubSub* pubSub, wEventType* events, size_t count)
 {
+	WINPR_ASSERT(pubSub);
+	WINPR_ASSERT(events || (count == 0));
 	if (pubSub->synchronized)
 		PubSub_Lock(pubSub);
 
@@ -114,6 +121,8 @@ int PubSub_Subscribe(wPubSub* pubSub, const char* EventName, pEventHandler Event
 {
 	wEventType* event;
 	int status = -1;
+	WINPR_ASSERT(pubSub);
+	WINPR_ASSERT(EventHandler);
 
 	if (pubSub->synchronized)
 		PubSub_Lock(pubSub);
@@ -141,6 +150,9 @@ int PubSub_Unsubscribe(wPubSub* pubSub, const char* EventName, pEventHandler Eve
 	size_t index;
 	wEventType* event;
 	int status = -1;
+	WINPR_ASSERT(pubSub);
+	WINPR_ASSERT(EventName);
+	WINPR_ASSERT(EventHandler);
 
 	if (pubSub->synchronized)
 		PubSub_Lock(pubSub);
@@ -170,11 +182,13 @@ int PubSub_Unsubscribe(wPubSub* pubSub, const char* EventName, pEventHandler Eve
 	return status;
 }
 
-int PubSub_OnEvent(wPubSub* pubSub, const char* EventName, void* context, wEventArgs* e)
+int PubSub_OnEvent(wPubSub* pubSub, const char* EventName, void* context, const wEventArgs* e)
 {
 	size_t index;
 	wEventType* event;
 	int status = -1;
+	WINPR_ASSERT(pubSub);
+	WINPR_ASSERT(e);
 
 	if (pubSub->synchronized)
 		PubSub_Lock(pubSub);
diff --git a/winpr/libwinpr/utils/test/TestPubSub.c b/winpr/libwinpr/utils/test/TestPubSub.c
index 1ec08340a..18157d931 100644
--- a/winpr/libwinpr/utils/test/TestPubSub.c
+++ b/winpr/libwinpr/utils/test/TestPubSub.c
@@ -15,18 +15,18 @@ int flags;
 int button;
 DEFINE_EVENT_END(MouseButton)
 
-static void MouseMotionEventHandler(void* context, MouseMotionEventArgs* e)
+static void MouseMotionEventHandler(void* context, const MouseMotionEventArgs* e)
 {
 	printf("MouseMotionEvent: x: %d y: %d\n", e->x, e->y);
 }
 
-static void MouseButtonEventHandler(void* context, MouseButtonEventArgs* e)
+static void MouseButtonEventHandler(void* context, const MouseButtonEventArgs* e)
 {
 	printf("MouseButtonEvent: x: %d y: %d flags: %d button: %d\n", e->x, e->y, e->flags, e->button);
 }
 
-static wEventType Node_Events[] = { DEFINE_EVENT_ENTRY(MouseMotion)
-	                                    DEFINE_EVENT_ENTRY(MouseButton) };
+static wEventType Node_Events[] = { DEFINE_EVENT_ENTRY(MouseMotion),
+	                                DEFINE_EVENT_ENTRY(MouseButton) };
 
 #define NODE_EVENT_COUNT (sizeof(Node_Events) / sizeof(wEventType))