diff --git a/lib/Makefile.Watcom b/lib/Makefile.Watcom
index 4807972f1..07f2a2d9a 100644
--- a/lib/Makefile.Watcom
+++ b/lib/Makefile.Watcom
@@ -80,7 +80,7 @@ LINK_ARG = $(OBJ_BASE)\dyn\wlink.arg
 LIB_ARG  = $(OBJ_BASE)\stat\wlib.arg
 
 # In order to process Makefile.inc wmake must be called with -u switch!
-!ifneq __MAKEOPTS__ -u
+!ifndef %MAKEFLAGS
 !error You MUST call wmake with the -u switch!
 !else
 !include Makefile.inc
diff --git a/src/Makefile.Watcom b/src/Makefile.Watcom
index 9b3479238..9fa3ab4a0 100644
--- a/src/Makefile.Watcom
+++ b/src/Makefile.Watcom
@@ -67,7 +67,7 @@ OBJ_DIR  = WC_Win32.obj
 LINK_ARG = $(OBJ_DIR)\wlink.arg
 
 # In order to process Makefile.inc wmake must be called with -u switch!
-!ifneq __MAKEOPTS__ -u
+!ifndef %MAKEFLAGS
 !error You MUST call wmake with the -u switch!
 !else
 !include Makefile.inc