diff --git a/common.mk b/common.mk
index 8f4330b9a6..c888815395 100644
--- a/common.mk
+++ b/common.mk
@@ -986,7 +986,7 @@ $(REVISION_H): $(srcdir)/version.h $(srcdir)/tool/file2lastrev.rb $(REVISION_FOR
 $(srcdir)/ext/ripper/ripper.c: $(srcdir)/ext/ripper/tools/preproc.rb $(srcdir)/parse.y id.h
 	$(ECHO) generating $@
 	$(Q) VPATH=$${PWD-`pwd`} && $(CHDIR) $(@D) && \
-	sed /AUTOGENERATED/q depend | \
+	sed -e 's/{\$$([^(){}]*)[^{}]*}//g' -e /AUTOGENERATED/q depend | \
 	$(exec) $(MAKE) -f - $(mflags) \
 		Q=$(Q) ECHO=$(ECHO) RM="$(RM)" top_srcdir=../.. srcdir=. VPATH="$${VPATH}" \
 		RUBY="$(BASERUBY)" PATH_SEPARATOR="$(PATH_SEPARATOR)"