diff --git a/src/test/regress/expected/isolation_insert_vs_vacuum.out b/src/test/regress/expected/isolation_insert_vs_vacuum.out
index 285a981d0..6583ff0c6 100644
--- a/src/test/regress/expected/isolation_insert_vs_vacuum.out
+++ b/src/test/regress/expected/isolation_insert_vs_vacuum.out
@@ -1,6 +1,6 @@
 Parsed test spec with 2 sessions
 
-starting permutation: s1-begin s1-insert s2-vacuum-analyze s1-commit
+starting permutation: s1-begin s1-insert s2-vacuum-analyze s2-wait s1-commit
 create_distributed_table
 ---------------------------------------------------------------------
 
@@ -14,7 +14,9 @@ step s1-insert:
 
 step s2-vacuum-analyze:
     VACUUM ANALYZE test_insert_vacuum;
-
+ <waiting ...>
+step s2-vacuum-analyze: <... completed>
+step s2-wait:
 step s1-commit:
     COMMIT;
 
diff --git a/src/test/regress/spec/isolation_insert_vs_vacuum.spec b/src/test/regress/spec/isolation_insert_vs_vacuum.spec
index 71991d1a2..7860855e1 100644
--- a/src/test/regress/spec/isolation_insert_vs_vacuum.spec
+++ b/src/test/regress/spec/isolation_insert_vs_vacuum.spec
@@ -39,8 +39,14 @@ step "s2-vacuum-full"
     VACUUM FULL test_insert_vacuum;
 }
 
+step "s2-wait" {}
+
 // INSERT and VACUUM ANALYZE should not block each other.
-permutation "s1-begin" "s1-insert" "s2-vacuum-analyze" "s1-commit"
+// vacuum analyze sometimes gets randomly blocked temporarily, but this is
+// resolved automatically. To avoid flaky output, we always trigger a
+// <waiting...> message using (*) and then we wait until vacuum analyze
+// actually completes.
+permutation "s1-begin" "s1-insert" "s2-vacuum-analyze"(*) "s2-wait" "s1-commit"
 
 // INSERT and VACUUM FULL should block each other.
 permutation "s1-begin" "s1-insert" "s2-vacuum-full" "s1-commit"