diff --git a/public/crtlib.c b/public/crtlib.c
index 5fd339a0..e53cccd4 100644
--- a/public/crtlib.c
+++ b/public/crtlib.c
@@ -320,7 +320,9 @@ const char* Q_timestamp( int format )
 		// Build a timestamp that can use for filename (ex: "Nov2006-26 (19.14.28)");
 		strftime( timestamp, sizeof( timestamp ), "%b%Y-%d_%H.%M.%S", crt_tm );
 		break;
-	default: return NULL;
+	default:
+		Q_snprintf( timestamp, sizeof( timestamp ), "%s: unknown format %d", __func__, format );
+		break;
 	}
 
 	return timestamp;
diff --git a/public/crtlib.h b/public/crtlib.h
index ef0f717f..2356d195 100644
--- a/public/crtlib.h
+++ b/public/crtlib.h
@@ -78,7 +78,7 @@ qboolean Q_stricmpext( const char *pattern, const char *text );
 qboolean Q_strnicmpext( const char *pattern, const char *text, size_t minimumlen );
 const byte *Q_memmem( const byte *haystack, size_t haystacklen, const byte *needle, size_t needlelen );
 void Q_memor( byte *XASH_RESTRICT dst, const byte *XASH_RESTRICT src, size_t len );
-const char *Q_timestamp( int format );
+const char *Q_timestamp( int format ) RETURNS_NONNULL;
 int Q_vsnprintf( char *buffer, size_t buffersize, const char *format, va_list args );
 int Q_snprintf( char *buffer, size_t buffersize, const char *format, ... ) FORMAT_CHECK( 3 );
 #define Q_strpbrk strpbrk
@@ -86,7 +86,7 @@ void COM_StripColors( const char *in, char *out );
 #define Q_memprint( val ) Q_pretifymem( val, 2 )
 char *Q_pretifymem( float value, int digitsafterdecimal );
 void COM_FileBase( const char *in, char *out, size_t size );
-const char *COM_FileExtension( const char *in );
+const char *COM_FileExtension( const char *in ) RETURNS_NONNULL;
 void COM_DefaultExtension( char *path, const char *extension, size_t size );
 void COM_ReplaceExtension( char *path, const char *extension, size_t size );
 void COM_ExtractFilePath( const char *path, char *dest );