diff --git a/tests/data/test1712 b/tests/data/test1712
index 198b5e17ad..5cdc642d09 100644
--- a/tests/data/test1712
+++ b/tests/data/test1712
@@ -55,7 +55,7 @@ Content-Type: application/x-www-form-urlencoded
 </protocol>
 <stderr mode="warn">
 Warning: %LOGDIR/config:1 Option 'data' uses argument with leading single quote.%SP
-Warning: It is probably a mistake. Consider double quotes.
+It is probably a mistake. Consider double quotes.
 </stderr>
 </verify>
 </testcase>
diff --git a/tests/runtests.pl b/tests/runtests.pl
index d8ac67a670..e8612d2756 100755
--- a/tests/runtests.pl
+++ b/tests/runtests.pl
@@ -1347,12 +1347,20 @@ sub singletest_check {
             normalize_text(\@actual);
         }
         if($filemode && ($filemode eq "warn")) {
-            map { 's/Warning: //' } (@validstderr);
-            map { 's/\r//' } (@validstderr);
-            map { 's/\n/ /' } (@validstderr);
-            map { 's/Warning: //' } (@actual);
-            map { 's/\r//' } (@actual);
-            map { 's/\n/ /' } (@actual);
+            for(@validstderr) {
+                s/Warning: //;
+                s/\r//;
+                s/\n/ /;
+            }
+            for(@actual) {
+                s/Warning: //;
+                s/\r//;
+                s/\n/ /;
+            }
+            my $v = join(@validstderr, "");
+            my $a = join(@actual, "");
+            @validstderr = $v;
+            @actual = $a;
         }
 
         if($hash{'nonewline'}) {