Index: b/extensions/Makefile
===================================================================
--- a/extensions/Makefile
+++ b/extensions/Makefile
@@ -32,6 +32,8 @@ link_defs:
 	@rm -f defs.h
 	@ln ../defs.h 
 
+defs.h: link_defs
+
 $(CONTRIB_SO): %.so: %.c defs.h
 	@if [ -f $*.mk ]; then \
 		$(MAKE) -f $*.mk; \