diff --git a/rtgui/preferences.cc b/rtgui/preferences.cc
index 94dc68e65..f6f80a2d3 100644
--- a/rtgui/preferences.cc
+++ b/rtgui/preferences.cc
@@ -2701,7 +2701,7 @@ void Preferences::extensionsChanged()
 
 void Preferences::extensionChanged()
 {
-    if (extension->get_text()[0] == '\0') {
+    if (extension->get_text().empty()) {
         addExt->set_sensitive(false);
         return;
     }