diff --git a/neo/d3xp/Game_local.cpp b/neo/d3xp/Game_local.cpp
index 9a617127..dc090372 100644
--- a/neo/d3xp/Game_local.cpp
+++ b/neo/d3xp/Game_local.cpp
@@ -2653,7 +2653,7 @@ void idGameLocal::CalcFov( float base_fov, float &fov_x, float &fov_y ) const {
 	// FIXME: somehow, this is happening occasionally
 	assert( fov_y > 0 );
 	if ( fov_y <= 0 ) {
-		Error( "idGameLocal::CalcFov: bad result, fov_y == %f, base_fov == ", fov_y, base_fov );
+		Error( "idGameLocal::CalcFov: bad result, fov_y == %f, base_fov == %f", fov_y, base_fov );
 	}
 
 	switch( r_aspectRatio.GetInteger() ) {
diff --git a/neo/game/Game_local.cpp b/neo/game/Game_local.cpp
index 0517b82e..524bc5d8 100644
--- a/neo/game/Game_local.cpp
+++ b/neo/game/Game_local.cpp
@@ -2387,7 +2387,7 @@ void idGameLocal::CalcFov( float base_fov, float &fov_x, float &fov_y ) const {
 	// FIXME: somehow, this is happening occasionally
 	assert( fov_y > 0 );
 	if ( fov_y <= 0 ) {
-		Error( "idGameLocal::CalcFov: bad result, fov_y == %f, base_fov == ", fov_y, base_fov );
+		Error( "idGameLocal::CalcFov: bad result, fov_y == %f, base_fov == %f", fov_y, base_fov );
 	}
 
 	switch( r_aspectRatio.GetInteger() ) {
diff --git a/neo/idlib/Parser.cpp b/neo/idlib/Parser.cpp
index 931fd52a..86a57d34 100644
--- a/neo/idlib/Parser.cpp
+++ b/neo/idlib/Parser.cpp
@@ -712,9 +712,9 @@ int idParser::ExpandBuiltinDefine( idToken *deftoken, define_t *define, idToken
 			curtime = ctime(&t);
 			(*token) = "\"";
 			token->Append( curtime+4 );
-			token[7] = '\0';
+			token[7] = NULL;
 			token->Append( curtime+20 );
-			token[10] = '\0';
+			token[10] = NULL;
 			token->Append( "\"" );
 			free(curtime);
 			token->type = TT_STRING;
@@ -731,7 +731,7 @@ int idParser::ExpandBuiltinDefine( idToken *deftoken, define_t *define, idToken
 			curtime = ctime(&t);
 			(*token) = "\"";
 			token->Append( curtime+11 );
-			token[8] = '\0';
+			token[8] = NULL;
 			token->Append( "\"" );
 			free(curtime);
 			token->type = TT_STRING;
diff --git a/neo/sound/snd_efxfile.cpp b/neo/sound/snd_efxfile.cpp
index cbf7fe15..594afe8b 100644
--- a/neo/sound/snd_efxfile.cpp
+++ b/neo/sound/snd_efxfile.cpp
@@ -273,7 +273,7 @@ bool idEFXFile::LoadFile( const char *filename, bool OSPath ) {
 	}
 
 	if ( !src.ExpectTokenString( "Version" ) ) {
-		return NULL;
+		return false;
 	}
 
 	if ( src.ParseInt() != 1 ) {
diff --git a/neo/sys/events.cpp b/neo/sys/events.cpp
index ffb8eb09..6932db45 100644
--- a/neo/sys/events.cpp
+++ b/neo/sys/events.cpp
@@ -528,7 +528,7 @@ sysEvent_t Sys_GetEvent() {
 
 #if SDL_VERSION_ATLEAST(2, 0, 0)
 		case SDL_TEXTINPUT:
-			if (ev.text.text && *ev.text.text) {
+			if (ev.text.text[0]) {
 				if (!ev.text.text[1])
 					c = *ev.text.text;
 				else
diff --git a/neo/ui/Window.cpp b/neo/ui/Window.cpp
index 32423341..6d4cbc99 100644
--- a/neo/ui/Window.cpp
+++ b/neo/ui/Window.cpp
@@ -2053,7 +2053,7 @@ bool idWindow::ParseRegEntry(const char *name, idParser *src) {
 	work = name;
 	work.ToLower();
 
-	idWinVar *var = GetWinVarByName(work, NULL);
+	idWinVar *var = GetWinVarByName(work, false);
 	if ( var ) {
 		for (int i = 0; i < NumRegisterVars; i++) {
 			if (idStr::Icmp(work, RegisterVars[i].name) == 0) {