diff --git a/xpcom/Makefile.in b/xpcom/Makefile.in
index 8af06ee85bd..ac811ddf906 100644
--- a/xpcom/Makefile.in
+++ b/xpcom/Makefile.in
@@ -90,3 +90,9 @@ endif
 
 include $(topsrcdir)/config/rules.mk
 
+regenerate-idl-parser:
+	$(PYTHON_PATH) \
+	  -I$(topsrcdir)/other-licenses/ply \
+	  -I$(topsrcdir)/xpcom/idl-parser \
+	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=$(topsrcdir)/xpcom/idl-parser --regen
+