diff --git a/src/ca65/error.c b/src/ca65/error.c
index f480fe961..fc984268b 100644
--- a/src/ca65/error.c
+++ b/src/ca65/error.c
@@ -72,7 +72,6 @@ void WarningMsg (const FilePos* Pos, unsigned WarnNum, va_list ap)
 	unsigned char 	Level;
 	const char*	Msg;
     } Warnings [WARN_COUNT-1] = {
-	{   1,	"Mask error"					},
        	{   2,  "Symbol `%s' is defined but never used" 	},
         {   2,  "Symbol `%s' is imported but never used"	},
 	{   1,  "Cannot track processor status byte"		},
diff --git a/src/ca65/error.h b/src/ca65/error.h
index c13cd6875..665664531 100644
--- a/src/ca65/error.h
+++ b/src/ca65/error.h
@@ -52,7 +52,6 @@
 /* Warning numbers */
 enum Warnings {
     WARN_NONE,	       	    	      	/* No warning */
-    WARN_MASK_ERROR,
     WARN_SYM_NOT_REFERENCED,
     WARN_IMPORT_NOT_REFERENCED,
     WARN_CANNOT_TRACK_STATUS,