Fix converting map to string
diff --git a/convert.go b/convert.go
index fc23eb6..be8de39 100644
--- a/convert.go
+++ b/convert.go
@@ -124,13 +124,19 @@
 				ret += ", "
 			}
 
+			keyitem, err := convertToString(key, options)
+
+			if err != nil {
+				return "", err
+			}
+
 			item, err := convertToString(val.MapIndex(key), options)
 
 			if err != nil {
 				return "", err
 			}
 
-			ret += item
+			ret += keyitem + ":" + item
 		}
 
 		return ret + "}", nil