diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3626aee0e..81e5af13f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -175,6 +175,14 @@ if(CMAKE_COMPILER_IS_GNUCC)
 			set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-format")
 		endif()
 	endif()
+	CHECK_C_COMPILER_FLAG (-Wimplicit-function-declaration Wimplicit-function-declaration)
+	if(Wimplicit-function-declaration)
+		set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wimplicit-function-declaration")
+	endif()
+	CHECK_C_COMPILER_FLAG (-Wredundant-decls Wredundant-decls)
+	if(Wredundant-decls)
+		set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wredundant-decls")
+	endif()
 	if(CMAKE_BUILD_TYPE STREQUAL "Release")
 		set(CMAKE_C_FLAGS_RELEASE "-DNDEBUG")
 		set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG")
diff --git a/include/freerdp/crypto/ber.h b/include/freerdp/crypto/ber.h
index 546b19c39..283444866 100644
--- a/include/freerdp/crypto/ber.h
+++ b/include/freerdp/crypto/ber.h
@@ -63,7 +63,6 @@ FREERDP_API BOOL ber_read_universal_tag(wStream* s, BYTE tag, BOOL pc);
 FREERDP_API int ber_write_universal_tag(wStream* s, BYTE tag, BOOL pc);
 FREERDP_API BOOL ber_read_application_tag(wStream* s, BYTE tag, int* length);
 FREERDP_API void ber_write_application_tag(wStream* s, BYTE tag, int length);
-FREERDP_API BOOL ber_read_application_tag(wStream* s, BYTE tag, int* length);
 FREERDP_API BOOL ber_read_enumerated(wStream* s, BYTE* enumerated, BYTE count);
 FREERDP_API void ber_write_enumerated(wStream* s, BYTE enumerated, BYTE count);
 FREERDP_API BOOL ber_read_contextual_tag(wStream* s, BYTE tag, int* length, BOOL pc);
diff --git a/include/freerdp/crypto/er.h b/include/freerdp/crypto/er.h
index 5fab63de3..3f70fef3b 100644
--- a/include/freerdp/crypto/er.h
+++ b/include/freerdp/crypto/er.h
@@ -68,7 +68,6 @@ FREERDP_API BOOL er_read_universal_tag(wStream* s, BYTE tag, BOOL pc);
 FREERDP_API void er_write_universal_tag(wStream* s, BYTE tag, BOOL pc);
 FREERDP_API BOOL er_read_application_tag(wStream* s, BYTE tag, int* length);
 FREERDP_API void er_write_application_tag(wStream* s, BYTE tag, int length, BOOL flag);
-FREERDP_API BOOL er_read_application_tag(wStream* s, BYTE tag, int* length);
 FREERDP_API BOOL er_read_enumerated(wStream* s, BYTE* enumerated, BYTE count);
 FREERDP_API void er_write_enumerated(wStream* s, BYTE enumerated, BYTE count, BOOL flag);
 FREERDP_API BOOL er_read_contextual_tag(wStream* s, BYTE tag, int* length, BOOL pc);
diff --git a/libfreerdp/primitives/prim_YUV.c b/libfreerdp/primitives/prim_YUV.c
index 24ff1a49a..a49fc38c5 100644
--- a/libfreerdp/primitives/prim_YUV.c
+++ b/libfreerdp/primitives/prim_YUV.c
@@ -24,7 +24,6 @@
 #include <freerdp/primitives.h>
 #include <freerdp/codec/color.h>
 
-#include "prim_internal.h"
 #include "prim_YUV.h"
 
 /**
diff --git a/rdtk/librdtk/rdtk_surface.h b/rdtk/librdtk/rdtk_surface.h
index efe7a879b..196943e0f 100644
--- a/rdtk/librdtk/rdtk_surface.h
+++ b/rdtk/librdtk/rdtk_surface.h
@@ -33,17 +33,5 @@ struct rdtk_surface
 	BYTE* data;
 	BOOL owner;
 };
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-rdtkSurface* rdtk_surface_new(rdtkEngine* engine, BYTE* data, int width, int height, int scanline);
-void rdtk_surface_free(rdtkSurface* surface);
-
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* RDTK_SURFACE_PRIVATE_H */