diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index ca19c0a4ef..d2f5fbe5de 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -3132,14 +3132,13 @@ Editor::convert_drop_to_paths (
 
 		if ((*i).substr (0,7) == "file://") {
 
-			string p = *i;
-			PBD::url_decode (p);
+			string const p = PBD::url_decode (*i);
 
 			// scan forward past three slashes
 
 			string::size_type slashcnt = 0;
 			string::size_type n = 0;
-			string::iterator x = p.begin();
+			string::const_iterator x = p.begin();
 
 			while (slashcnt < 3 && x != p.end()) {
 				if ((*x) == '/') {
diff --git a/libs/pbd/convert.cc b/libs/pbd/convert.cc
index 49650ab6e9..3d968d0627 100644
--- a/libs/pbd/convert.cc
+++ b/libs/pbd/convert.cc
@@ -178,94 +178,23 @@ int_from_hex (char hic, char loc)
 	return lo + (16 * hi);
 }
 
-void
-url_decode (string& url)
+string
+url_decode (string const & url)
 {
-	string::iterator last;
-	string::iterator next;
+	string decoded;
 
-	for (string::iterator i = url.begin(); i != url.end(); ++i) {
-		if ((*i) == '+') {
-			*i = ' ';
-		}
-	}
-
-	if (url.length() <= 3) {
-		return;
-	}
-
-	last = url.end();
-
-	--last; /* points at last char */
-	--last; /* points at last char - 1 */
-
-	for (string::iterator i = url.begin(); i != last; ) {
-
-		if (*i == '%') {
-
-			next = i;
-
-			url.erase (i);
-			
-			i = next;
-			++next;
-			
-			if (isxdigit (*i) && isxdigit (*next)) {
-				/* replace first digit with char */
-				*i = int_from_hex (*i,*next);
-				++i; /* points at 2nd of 2 digits */
-				url.erase (i);
-			}
+	for (string::size_type i = 0; i < url.length(); ++i) {
+		if (url[i] == '+') {
+			decoded += ' ';
+		} else if (url[i] == '%' && i <= url.length() - 3) {
+			decoded += char (int_from_hex (url[i + 1], url[i + 2]));
+			i += 2;
 		} else {
-			++i;
-		}
-	}
-}
-
-void
-url_decode (ustring& url)
-{
-	ustring::iterator last;
-	ustring::iterator next;
-
-	for (ustring::iterator i = url.begin(); i != url.end(); ++i) {
-		if ((*i) == '+') {
-			next = i;
-			++next;
-			url.replace (i, next, 1, ' ');
+			decoded += url[i];
 		}
 	}
 
-	if (url.length() <= 3) {
-		return;
-	}
-
-	last = url.end();
-
-	--last; /* points at last char */
-	--last; /* points at last char - 1 */
-
-	for (ustring::iterator i = url.begin(); i != last; ) {
-
-		if (*i == '%') {
-
-			next = i;
-
-			url.erase (i);
-			
-			i = next;
-			++next;
-			
-			if (isxdigit (*i) && isxdigit (*next)) {
-				/* replace first digit with char */
-				url.replace (i, next, 1, (gunichar) int_from_hex (*i,*next));
-				++i; /* points at 2nd of 2 digits */
-				url.erase (i);
-			}
-		} else {
-			++i;
-		}
-	}
+	return decoded;
 }
 
 #if 0
diff --git a/libs/pbd/pbd/convert.h b/libs/pbd/pbd/convert.h
index 7bf922e94f..937b5a7a9d 100644
--- a/libs/pbd/pbd/convert.h
+++ b/libs/pbd/pbd/convert.h
@@ -35,8 +35,7 @@ int     atoi (const std::string&);
 int32_t atol (const std::string&);
 int64_t atoll (const std::string&);
 double  atof (const std::string&);
-void    url_decode (std::string&);
-void    url_decode (Glib::ustring&);
+std::string url_decode (std::string const &);
 
 std::string capitalize (const std::string&);
 
diff --git a/libs/pbd/test/convert_test.cc b/libs/pbd/test/convert_test.cc
index 43e6546716..8b818deea1 100644
--- a/libs/pbd/test/convert_test.cc
+++ b/libs/pbd/test/convert_test.cc
@@ -8,7 +8,6 @@ using namespace std;
 void
 ConvertTest::testUrlDecode ()
 {
-	string url = "http://foo.bar.baz/A%20B%20C%20.html";
-	PBD::url_decode (url);
-	CPPUNIT_ASSERT_EQUAL (url, string ("http://foo.bar.baz/A B C .html"));
+	string const url = "http://foo.bar.baz/A%20B%20C%20+42.html";
+	CPPUNIT_ASSERT_EQUAL (PBD::url_decode (url), string ("http://foo.bar.baz/A B C  42.html"));
 }