diff --git a/src/pl/plperl/GNUmakefile b/src/pl/plperl/GNUmakefile
index 01588d016a..61376cdde7 100644
--- a/src/pl/plperl/GNUmakefile
+++ b/src/pl/plperl/GNUmakefile
@@ -124,6 +124,7 @@ submake:
 
 clean distclean maintainer-clean: clean-lib
 	rm -f SPI.c Util.c $(OBJS) perlchunks.h plperl_opmask.h
+	rm -f sql/plperl_env.sql expected/plperl_env.out
 	rm -rf $(pg_regress_clean_files)
 ifeq ($(PORTNAME), win32)
 	rm -f $(perlwithver).def
diff --git a/src/pl/plperl/input/plperl_env.source b/src/pl/plperl/input/plperl_env.source
index 8fe526e1b8..49f03acb1d 100644
--- a/src/pl/plperl/input/plperl_env.source
+++ b/src/pl/plperl/input/plperl_env.source
@@ -50,3 +50,6 @@ $$
    }
 
 $$ LANGUAGE plperl;
+
+-- clean up to simplify cross-version upgrade testing
+DROP FUNCTION get_environ();
diff --git a/src/pl/plperl/output/plperl_env.source b/src/pl/plperl/output/plperl_env.source
index 37b7e23d5c..ef75d5d555 100644
--- a/src/pl/plperl/output/plperl_env.source
+++ b/src/pl/plperl/output/plperl_env.source
@@ -47,3 +47,5 @@ $$
 $$ LANGUAGE plperl;
 WARNING:  attempted alteration of $ENV{TEST_PLPERL_ENV_FOO} at line 12.
 NOTICE:  environ unaffected
+-- clean up to simplify cross-version upgrade testing
+DROP FUNCTION get_environ();