--- a/mk/catsql.py
+++ b/mk/catsql.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/python3
 
 """Prints out SQL files with psql command execution.
 
--- a/mk/grantfu.py
+++ b/mk/grantfu.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/python3
 
 # GrantFu - GRANT/REVOKE generator for Postgres
 # 
--- a/mk/common-pgxs.mk
+++ b/mk/common-pgxs.mk
@@ -62,7 +62,7 @@ include $(PGXS)
 
 # when compiling locally and with postgres without python,
 # the variable may be empty
-PYTHON := $(if $(PYTHON),$(PYTHON),python)
+PYTHON := python3
 
 #
 # common tools
