diff --git a/py/mkrules.mk b/py/mkrules.mk
index fab29b2b22..c36f0f9cd8 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -36,7 +36,7 @@ $(Q)$(CC) $(CFLAGS) -c -MD -o $@ $<
 @# The following fixes the dependency file.
 @# See http://make.paulandlesley.org/autodep.html for details.
 @$(CP) $(@:.o=.d) $(@:.o=.P); \
-  $(SED) -e 's/#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//' \
+  $(SED) -e 's/#.*//' -e 's/^.*:  *//' -e 's/ *\\$$//' \
       -e '/^$$/ d' -e 's/$$/ :/' < $(@:.o=.d) >> $(@:.o=.P); \
   $(RM) -f $(@:.o=.d)
 endef