--- libmalloc/libmalloc-374.120.1/xcodescripts/manpages.sh
+++ libmalloc/libmalloc-67/xcodescripts/manpages.sh
@@ -3,8 +3,7 @@
 if [ "$ACTION" = installhdrs ]; then exit 0; fi
 if [[ "$PLATFORM_NAME" != "macosx" ]]; then exit 0; fi
 
-UNIFDEF_FLAGS=""
-
+UNIFDEF_FLAGS="-D__OPEN_SOURCE__"
 MANPAGES_LIST="${SRCROOT}/man/manpages.lst"
 FILES=$(find -E ${SRCROOT} -regex '.*/[^.]+\.[0-9]' -type f)