diff --git a/t/90_pos.t b/t/90_pos.t
index 066e58b98..cc2a15b61 100644
--- a/t/90_pos.t
+++ b/t/90_pos.t
@@ -12,14 +12,57 @@ my $MSGUNIQ = `which msguniq`;
 chomp $MSGUNIQ;
 ok($MSGUNIQ,"msguniq required to test po files");
 
+sub test_duplicated {
+    my $file = shift;
+    open my $in,"<", $file or die "$! $file";
+    my $msgid;
+    my %found;
+    my $string;
+    my @warnings;
+    while (my $line = <$in>) {
+        my ($msgstr) = $line =~ /^msgstr/;
+        if ($msgstr && $string) {
+            my $string_lc = uc($string);
+            if($found{$string_lc}) {
+                push@warnings,("'$string' duplicated in line ".$found{$string_lc}." and $.");
+            }
+            $found{$string_lc}=$.;
+            $string = undef;
+            next;
+        }
+        my ($string1) = $line =~ /^msgid "(.*)"/;
+        if (defined $string1) {
+            $string = $string1;
+            next;
+        }
+        if (!defined $string1 && defined $string) {
+            my ($string2) = $line =~ /^"(.*)"/;
+            if (defined $string2) {
+                $msgid=0;
+                $string = "$string$string2";
+            }
+        }
+        next if !$string;
+    }
+
+    close $in;
+    if (@warnings){
+        diag("Warning: duplicated strings found in $file");
+        diag(join("\n",map {"  - $_" } @warnings));
+    }
+}
+
 my @po;
 opendir my $po,$DIR_PO or die "$! $DIR_PO";
 while (my $file = readdir $po) {
-    next if $file !~ /\.po/;
+    next if $file !~ /\.po$/;
     push @po,($file);
 }
 closedir $po;
 
+for my $file (@po) {
+    test_duplicated("$DIR_PO/$file");
+}
 
 SKIP: {
     skip("Missing msguniq", scalar @po) if !$MSGUNIQ;