diff --git a/gtk/gtkcssparser.c b/gtk/gtkcssparser.c
index bedfdec1c1..04242aaa71 100644
--- a/gtk/gtkcssparser.c
+++ b/gtk/gtkcssparser.c
@@ -669,15 +669,16 @@ _gtk_css_number_value_parse (GtkCssParser           *parser,
             break;
         }
 
-      g_free (unit_name);
-
       if (i >= G_N_ELEMENTS (units))
         {
           _gtk_css_parser_error (parser, "`%s' is not a valid unit.", unit_name);
+          g_free (unit_name);
           return NULL;
         }
 
       unit = units[i].unit;
+
+      g_free (unit_name);
     }
   else
     {