diff --git a/src/test/modules/brin/Makefile b/src/test/modules/brin/Makefile
index 18c5cafd5e..912dca8009 100644
--- a/src/test/modules/brin/Makefile
+++ b/src/test/modules/brin/Makefile
@@ -1,6 +1,9 @@
 # src/test/modules/brin/Makefile
 
-EXTRA_CLEAN = ./isolation_output
+# Note: because we don't tell the Makefile there are any regression tests,
+# we have to clean those result files explicitly
+EXTRA_CLEAN = $(pg_regress_clean_files) ./isolation_output
+
 EXTRA_INSTALL=contrib/pageinspect
 
 ISOLATIONCHECKS=summarization-and-inprogress-insertion