diff --git a/winbuild/MakefileBuild.vc b/winbuild/MakefileBuild.vc
index 5cda3900f..3125c21b8 100644
--- a/winbuild/MakefileBuild.vc
+++ b/winbuild/MakefileBuild.vc
@@ -239,6 +239,7 @@ ZLIB_LIB_DIR = $(DEVEL_LIB)
 !IF "$(WITH_ZLIB)"=="dll"
 !IF EXISTS("$(ZLIB_LIB_DIR)\zlibwapi.lib")
 ZLIB_LIBS = zlibwapi.lib
+ADDITIONAL_ZLIB_CFLAGS = /DZLIB_WINAPI
 !ELSEIF EXISTS("$(ZLIB_LIB_DIR)\zdll.lib")
 ZLIB_LIBS   = zdll.lib
 !ELSE
@@ -249,6 +250,7 @@ ZLIB        = dll
 !ELSEIF "$(WITH_ZLIB)"=="static"
 !IF EXISTS("$(ZLIB_LIB_DIR)\zlibstat.lib")
 ZLIB_LIBS   = zlibstat.lib
+ADDITIONAL_ZLIB_CFLAGS = /DZLIB_WINAPI
 !ELSEIF EXISTS("$(ZLIB_LIB_DIR)\zlib.lib")
 ZLIB_LIBS   = zlib.lib
 !ELSE
@@ -259,7 +261,7 @@ ZLIB        = static
 !ENDIF
 
 !IFDEF USE_ZLIB
-ZLIB_CFLAGS = /DHAVE_ZLIB_H /DHAVE_ZLIB /DHAVE_LIBZ /I"$(ZLIB_INC_DIR)"
+ZLIB_CFLAGS = /DHAVE_ZLIB_H /DHAVE_ZLIB /DHAVE_LIBZ $(ADDITIONAL_ZLIB_CFLAGS) /I"$(ZLIB_INC_DIR)"
 !ENDIF