--- a/usr/src/Makefile.master
+++ b/usr/src/Makefile.master
@@ -282,6 +282,8 @@ INS.symlink=        $(RM) $@; $(SYMLINK) $(INSLINKTARGET) $@
 # python scripts to the proto area. This is overridden by makefiles to
 # select to the correct version.
 PYSHEBANG=     $(PYTHON)
+$(BUILDPY3)PYSHEBANG=  $(PYTHON3)
+$(BUILDPY2)PYSHEBANG=  $(PYTHON)

 #
 # Python bakes the mtime of the .py file into the compiled .pyc and