diff --git a/source/texk/web2c/mplibdir/mp.w b/source/texk/web2c/mplibdir/mp.w
index e0999e187f5b53bd3393896a3e904f8b8235d4ea..9c3e36844e3da9fe85de19057f8ad01b4d559e0b 100644
--- a/source/texk/web2c/mplibdir/mp.w
+++ b/source/texk/web2c/mplibdir/mp.w
@@ -128,7 +128,7 @@ typedef int integer;
 #define MPOST_ABS abs
 #else
 /* See source/texk/web2c/w2c/config.h */
-#if INTEGER_TYPE == long 
+#if INTEGER_MAX == LONG_MAX /* this should mean INTEGER_TYPE == long */
 #ifdef HAVE_LABS
 #define MPOST_ABS labs
 #else