diff --git a/src/test/isolation/expected/plpgsql-toast.out b/src/test/isolation/expected/plpgsql-toast.out
index 43411533f1d..fc557da5e77 100644
--- a/src/test/isolation/expected/plpgsql-toast.out
+++ b/src/test/isolation/expected/plpgsql-toast.out
@@ -22,7 +22,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
  <waiting ...>
@@ -35,6 +35,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(x) = 6000
 step assign1: <... completed>
 
 starting permutation: lock assign2 vacuum unlock
@@ -59,7 +60,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
  <waiting ...>
@@ -72,6 +73,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(x) = 6000
 step assign2: <... completed>
 
 starting permutation: lock assign3 vacuum unlock
@@ -97,7 +99,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
  <waiting ...>
@@ -110,6 +112,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(r) = 6004
 step assign3: <... completed>
 
 starting permutation: lock assign4 vacuum unlock
@@ -134,7 +137,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
  <waiting ...>
@@ -147,6 +150,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(r) = 6004
 step assign4: <... completed>
 
 starting permutation: lock assign5 vacuum unlock
@@ -173,7 +177,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
  <waiting ...>
@@ -186,4 +190,5 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(r) = 6002
 step assign5: <... completed>
diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c
index 2f039b83eea..6ab19b1e597 100644
--- a/src/test/isolation/isolationtester.c
+++ b/src/test/isolation/isolationtester.c
@@ -187,18 +187,6 @@ main(int argc, char **argv)
 								 blackholeNoticeProcessor,
 								 NULL);
 
-		/*
-		 * Suppress NOTIFY messages, which otherwise pop into results at odd
-		 * places.
-		 */
-		res = PQexec(conns[i], "SET client_min_messages = warning;");
-		if (PQresultStatus(res) != PGRES_COMMAND_OK)
-		{
-			fprintf(stderr, "message level setup failed: %s", PQerrorMessage(conns[i]));
-			exit(1);
-		}
-		PQclear(res);
-
 		/* Get the backend pid for lock wait checking. */
 		res = PQexec(conns[i], "SELECT pg_catalog.pg_backend_pid()");
 		if (PQresultStatus(res) == PGRES_TUPLES_OK)
@@ -899,7 +887,7 @@ printResultSet(PGresult *res)
 static void
 isotesterNoticeProcessor(void *arg, const char *message)
 {
-	fprintf(stderr, "%s: %s", (char *) arg, message);
+	printf("%s: %s", (char *) arg, message);
 }
 
 /* notice processor, hides the message */
diff --git a/src/test/isolation/specs/insert-conflict-specconflict.spec b/src/test/isolation/specs/insert-conflict-specconflict.spec
index 3a70484fc29..2d16fae1b1b 100644
--- a/src/test/isolation/specs/insert-conflict-specconflict.spec
+++ b/src/test/isolation/specs/insert-conflict-specconflict.spec
@@ -51,6 +51,9 @@ session "s1"
 setup
 {
   SET default_transaction_isolation = 'read committed';
+  -- on very slow machines, the notices come out in unpredictable order,
+  -- so hide them
+  SET client_min_messages = warning;
   SET spec.session = 1;
 }
 step "s1_begin"  { BEGIN; }
@@ -61,6 +64,9 @@ session "s2"
 setup
 {
   SET default_transaction_isolation = 'read committed';
+  -- on very slow machines, the notices come out in unpredictable order,
+  -- so hide them
+  SET client_min_messages = warning;
   SET spec.session = 2;
 }
 step "s2_begin"  { BEGIN; }
diff --git a/src/test/isolation/specs/plpgsql-toast.spec b/src/test/isolation/specs/plpgsql-toast.spec
index e6228c9ef68..fe7090addbb 100644
--- a/src/test/isolation/specs/plpgsql-toast.spec
+++ b/src/test/isolation/specs/plpgsql-toast.spec
@@ -40,7 +40,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
 }
@@ -56,7 +56,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
 }
@@ -73,7 +73,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
 }
@@ -89,7 +89,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
 }
@@ -107,7 +107,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
 }