diff --git a/gtk/gtkdropdown.c b/gtk/gtkdropdown.c
index 30cb3fa172764c07585368ec431b72ddf77f4a87..bc2b8650cace8aeb70a8ec6bcabc6f73eeb12812 100644
--- a/gtk/gtkdropdown.c
+++ b/gtk/gtkdropdown.c
@@ -226,7 +226,7 @@ update_filter (GtkDropDown *self)
       if (self->expression)
         {
           filter = GTK_FILTER (gtk_string_filter_new (gtk_expression_ref (self->expression)));
-          gtk_string_filter_set_match_mode (GTK_STRING_FILTER (filter), GTK_STRING_FILTER_MATCH_MODE_PREFIX);
+          gtk_string_filter_set_match_mode (GTK_STRING_FILTER (filter), GTK_STRING_FILTER_MATCH_MODE_SUBSTRING);
         }
       else
         filter = GTK_FILTER (gtk_every_filter_new ());