diff --git a/libfreerdp/core/nla.c b/libfreerdp/core/nla.c
index 2b4b71992..875c0ae73 100644
--- a/libfreerdp/core/nla.c
+++ b/libfreerdp/core/nla.c
@@ -1245,6 +1245,7 @@ rdpCredssp* credssp_new(freerdp* instance, rdpTransport* transport, rdpSettings*
 		ZeroMemory(&credssp->negoToken, sizeof(SecBuffer));
 		ZeroMemory(&credssp->pubKeyAuth, sizeof(SecBuffer));
 		ZeroMemory(&credssp->authInfo, sizeof(SecBuffer));
+		SecInvalidateHandle(&credssp->context);
 
 		if (credssp->server)
 		{
diff --git a/libfreerdp/core/peer.c b/libfreerdp/core/peer.c
index 3806a736e..eb4ad60ea 100644
--- a/libfreerdp/core/peer.c
+++ b/libfreerdp/core/peer.c
@@ -272,6 +272,7 @@ static int peer_recv_callback(rdpTransport* transport, wStream* s, void* extra)
 				sspi_CopyAuthIdentity(&client->identity, &(rdp->nego->transport->credssp->identity));
 				IFCALLRET(client->Logon, client->authenticated, client, &client->identity, TRUE);
 				credssp_free(rdp->nego->transport->credssp);
+				rdp->nego->transport->credssp = NULL;
 			}
 			else
 			{
diff --git a/libfreerdp/core/transport.c b/libfreerdp/core/transport.c
index a9a710511..4afec5a12 100644
--- a/libfreerdp/core/transport.c
+++ b/libfreerdp/core/transport.c
@@ -159,6 +159,7 @@ BOOL transport_connect_nla(rdpTransport* transport)
 			"If credentials are valid, the NTLMSSP implementation may be to blame.\n");
 
 		credssp_free(transport->credssp);
+		transport->credssp = NULL;
 		return FALSE;
 	}
 
@@ -292,6 +293,7 @@ BOOL transport_accept_nla(rdpTransport* transport)
 	{
 		fprintf(stderr, "client authentication failure\n");
 		credssp_free(transport->credssp);
+		transport->credssp = NULL;
 		return FALSE;
 	}
 
diff --git a/winpr/libwinpr/sspi/sspi.c b/winpr/libwinpr/sspi/sspi.c
index 8747e3f01..96c959995 100644
--- a/winpr/libwinpr/sspi/sspi.c
+++ b/winpr/libwinpr/sspi/sspi.c
@@ -248,7 +248,7 @@ void* sspi_SecureHandleGetLowerPointer(SecHandle* handle)
 {
 	void* pointer;
 
-	if (!handle)
+	if (!handle || !SecIsValidHandle(handle))
 		return NULL;
 
 	pointer = (void*) ~((size_t) handle->dwLower);
@@ -268,7 +268,7 @@ void* sspi_SecureHandleGetUpperPointer(SecHandle* handle)
 {
 	void* pointer;
 
-	if (!handle)
+	if (!handle || !SecIsValidHandle(handle))
 		return NULL;
 
 	pointer = (void*) ~((size_t) handle->dwUpper);
@@ -839,7 +839,7 @@ SECURITY_STATUS SEC_ENTRY CompleteAuthToken(PCtxtHandle phContext, PSecBufferDes
 
 SECURITY_STATUS SEC_ENTRY DeleteSecurityContext(PCtxtHandle phContext)
 {
-	char* Name;
+	char* Name = NULL;
 	SECURITY_STATUS status;
 	SecurityFunctionTableA* table;