diff --git a/mvwrap/mvwrap b/mvwrap/mvwrap
index aa76386..3de8061 100755
--- a/mvwrap/mvwrap
+++ b/mvwrap/mvwrap
@@ -46,7 +46,11 @@ close ($target);
 if ($DEBUG) { print @target; }
 
 unless ( scalar(@source) == scalar(@target) ) {
-	die "source and target don't have the same number of lines";
+	die "Aborting. Source and target list don't have the same number of lines.\n";
+}
+
+if (&check_unique(@target)) {
+	die "Aborting. You're trying to move multiple files to the same name.\n";
 }
 
 $i=0;
@@ -62,3 +66,15 @@ while ( $i < scalar(@source) ) {
 	}
 	$i++;
 }
+
+# returns 0 if all entries in @target_list are unique. 1 if not.
+sub check_unique (@target_list){
+	my(@target_list, %seen, @uniqu);
+	@target_list = @_;
+	%seen = ();
+	@uniqu = grep { ! $seen{$_} ++ } @target_list;
+	unless (scalar(@uniqu) == scalar(@target) ) {
+		return 1;
+	}
+	return 0;
+}