Pass the -J option to wrc to avoid including installed headers.
diff --git a/Make.rules.in b/Make.rules.in
index affddee..90cf965 100644
--- a/Make.rules.in
+++ b/Make.rules.in
@@ -70,11 +70,12 @@
WRC = $(TOOLSDIR)/tools/wrc/wrc
WMC = $(TOOLSDIR)/tools/wmc/wmc
WIDL = $(TOOLSDIR)/tools/widl/widl
-LDPATH = @LDPATH@
-DLLDIR = $(TOPOBJDIR)/dlls
-LIBWINE = -L$(TOPOBJDIR)/library -lwine
-LIBUNICODE= -L$(TOPOBJDIR)/unicode -lwine_unicode
-LIBUUID = -L$(TOPOBJDIR)/ole -lwine_uuid
+WRCFLAGS = -J -m $(EXTRAWRCFLAGS)
+LDPATH = @LDPATH@
+DLLDIR = $(TOPOBJDIR)/dlls
+LIBWINE = -L$(TOPOBJDIR)/library -lwine
+LIBUNICODE = -L$(TOPOBJDIR)/unicode -lwine_unicode
+LIBUUID = -L$(TOPOBJDIR)/ole -lwine_uuid
@SET_MAKE@