diff --git a/src/build/Common.gmake b/src/build/Common.gmake
index f370cb1404379b4b884c935e21b7e87b4be37b90..0ab0f6fa928d66a6b320eb2aee1e411604ba8603 100644
--- a/src/build/Common.gmake
+++ b/src/build/Common.gmake
@@ -214,7 +214,7 @@ ifndef os
 endif
 os      :=	$(shell echo $(os) | tr '[A-Z]' '[a-z]' | tr ' ' '_')
 
-ifneq ($(os),Win32)
+ifneq ($(os),win32)
  CFLAGS +=	-DPREFER_POLL
 endif