diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index 98a0a22221ed..a3290c0fb111 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -3780,7 +3780,11 @@ int XREMain::XRE_mainStartup(bool* aExitFlag) {
   // consistently.
 
   // Set program name to the one defined in application.ini.
-  g_set_prgname(gAppData->remotingName);
+  {
+    nsAutoCString program(gAppData->name);
+    ToLowerCase(program);
+    g_set_prgname(program.get());
+  }
 
   // Initialize GTK here for splash.
 
diff --git a/widget/gtk/nsAppShell.cpp b/widget/gtk/nsAppShell.cpp
index 7b920eb2d88c..a4246649abf3 100644
--- a/widget/gtk/nsAppShell.cpp
+++ b/widget/gtk/nsAppShell.cpp
@@ -24,7 +24,6 @@
 #  include "WakeLockListener.h"
 #endif
 #include "gfxPlatform.h"
-#include "nsAppRunner.h"
 #include "ScreenHelperGTK.h"
 #include "HeadlessScreenHelper.h"
 #include "mozilla/widget/ScreenManager.h"
@@ -176,9 +175,13 @@ nsresult nsAppShell::Init() {
       // See https://bugzilla.gnome.org/show_bug.cgi?id=747634
       //
       // Only bother doing this for the parent process, since it's the one
-      // creating top-level windows.
-      if (gAppData) {
-        gdk_set_program_class(gAppData->remotingName);
+      // creating top-level windows. (At this point, a child process hasn't
+      // received the list of registered chrome packages, so the
+      // GetBrandShortName call would fail anyway.)
+      nsAutoString brandName;
+      mozilla::widget::WidgetUtils::GetBrandShortName(brandName);
+      if (!brandName.IsEmpty()) {
+        gdk_set_program_class(NS_ConvertUTF16toUTF8(brandName).get());
       }
     }
   }