diff --git a/Include/errcode.h b/Include/errcode.h
index 068331708bf..a8fe4584177 100644
--- a/Include/errcode.h
+++ b/Include/errcode.h
@@ -30,7 +30,7 @@ redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #define E_NOMEM		15	/* Ran out of memory */
 #define E_DONE		16	/* Parsing complete */
 #define E_ERROR		17	/* Execution error */
-#define E_TABSPACE	18	/* Invalid indentation detected */
+#define E_TABSPACE	18	/* Inconsistent mixing of tabs and spaces */
 #define E_OVERFLOW      19	/* Node had too many children */
 #define E_TOODEEP	20	/* Too many indentation levels */
 #define E_DEDENT	21	/* No matching outer block for dedent */