diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 05bf201435..4c0743bb03 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -101,7 +101,7 @@ endif
 # This places the generated .def file in srcdir, since it is expected to be there.
 # (The one from a tarball is)
 gtk.def: gtk.symbols
-	(echo -e EXPORTS; $(CPP) -P -DINCLUDE_VARIABLES -DG_OS_WIN32 -DALL_FILES - <$(srcdir)/gtk.symbols | sed -e '/^$$/d' -e 's/^/	/' -e 's/G_GNUC_[^ ]*//g') > $(srcdir)/gtk.def
+	(echo -e EXPORTS; $(CPP) -P -DINCLUDE_VARIABLES -DG_OS_WIN32 -DALL_FILES - <$(srcdir)/gtk.symbols | $(SED) -e '/^$$/d' -e 's/^/	/' -e 's/G_GNUC_[^ ]*//g') > $(srcdir)/gtk.def
 
 gtkalias.h: gtk.symbols
 	  $(PERL) $(srcdir)/makegtkalias.pl < $(srcdir)/gtk.symbols > gtkalias.h