diff --git a/src/mred/gc2/Makefile.in b/src/mred/gc2/Makefile.in
index 271d352a1b..72fd98a870 100644
--- a/src/mred/gc2/Makefile.in
+++ b/src/mred/gc2/Makefile.in
@@ -431,7 +431,7 @@ xsrc/wxs_win.cc: $(srcdir)/../wxs/wxs_win.cxx $(XFORMDEP) $(XFORMPRECOMPDEP)
 xsrc/wxJPEG.cc: $(srcdir)/../../wxcommon/wxJPEG.cxx $(XFORMDEP) $(XFORMPRECOMPDEP)
 	$(XFORMWP) xsrc/wxJPEG.cc $(srcdir)/../../wxcommon/wxJPEG.cxx
 
-GCPREINC = -include $(srcdir)/../../mzscheme/gc2/gc2.h
+GCPREINC = -DSCHEME_THREADLOCAL_H -include $(srcdir)/../../mzscheme/gc2/gc2.h
 POSTFLAGS = $(OPTIONS) @COMPFLAGS@ @PROFFLAGS@ @CFLAGS@
 XXPOSTFLAGS = $(OPTIONS) @COMPFLAGS@ @PROFFLAGS@ @CXXFLAGS@