diff --git a/browser/components/shell/moz.build b/browser/components/shell/moz.build
index 28cf72a31e80..d4a234b4a069 100644
--- a/browser/components/shell/moz.build
+++ b/browser/components/shell/moz.build
@@ -4,6 +4,11 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+# For BinaryPath::GetLong for Windows
+LOCAL_INCLUDES += [
+    '/xpcom/build'
+]
+
 XPCSHELL_TESTS_MANIFESTS += ['test/unit/xpcshell.ini']
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
diff --git a/browser/components/shell/nsWindowsShellService.cpp b/browser/components/shell/nsWindowsShellService.cpp
index 288ca84aa484..52631992721f 100644
--- a/browser/components/shell/nsWindowsShellService.cpp
+++ b/browser/components/shell/nsWindowsShellService.cpp
@@ -5,6 +5,7 @@
 
 #include "nsWindowsShellService.h"
 
+#include "BinaryPath.h"
 #include "city.h"
 #include "imgIContainer.h"
 #include "imgIRequest.h"
@@ -228,13 +229,10 @@ nsWindowsShellService::IsDefaultBrowser(bool aStartupCheck,
     return NS_OK;
   }
 
-  wchar_t exePath[MAX_BUF] = L"";
-  if (!::GetModuleFileNameW(0, exePath, MAX_BUF)) {
-    return NS_OK;
-  }
-  // Convert the path to a long path since GetModuleFileNameW returns the path
-  // that was used to launch Firefox which is not necessarily a long path.
-  if (!::GetLongPathNameW(exePath, exePath, MAX_BUF)) {
+  wchar_t exePath[MAXPATHLEN] = L"";
+  nsresult rv = BinaryPath::GetLong(exePath);
+
+  if (NS_FAILED(rv)) {
     return NS_OK;
   }
 
diff --git a/xpcom/build/BinaryPath.h b/xpcom/build/BinaryPath.h
index 0160d7e0d0e5..8ec672f715c2 100644
--- a/xpcom/build/BinaryPath.h
+++ b/xpcom/build/BinaryPath.h
@@ -20,6 +20,8 @@
 #include "mozilla/UniquePtrExtensions.h"
 
 #ifdef MOZILLA_INTERNAL_API
+#include "nsCOMPtr.h"
+#include "nsIFile.h"
 #include "nsString.h"
 #endif
 
@@ -41,13 +43,51 @@ public:
     return NS_OK;
   }
 
+  static nsresult GetLong(wchar_t aResult[MAXPATHLEN])
+  {
+    static bool cached = false;
+    static wchar_t exeLongPath[MAXPATHLEN] = L"";
+
+    if (!cached) {
+      nsresult rv = GetW(nullptr, exeLongPath);
+
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+
+      if (!::GetLongPathNameW(exeLongPath, exeLongPath, MAXPATHLEN)) {
+        return NS_ERROR_FAILURE;
+      }
+
+      cached = true;
+    }
+
+    if (wcscpy_s(aResult, MAXPATHLEN, exeLongPath)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    return NS_OK;
+  }
+
 private:
   static nsresult GetW(const char* argv0, wchar_t aResult[MAXPATHLEN])
   {
-    if (::GetModuleFileNameW(0, aResult, MAXPATHLEN)) {
-      return NS_OK;
+    static bool cached = false;
+    static wchar_t moduleFileName[MAXPATHLEN] = L"";
+
+    if (!cached) {
+      if (!::GetModuleFileNameW(0, moduleFileName, MAXPATHLEN)) {
+        return NS_ERROR_FAILURE;
+      }
+
+      cached = true;
     }
-    return NS_ERROR_FAILURE;
+
+    if (wcscpy_s(aResult, MAXPATHLEN, moduleFileName)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    return NS_OK;
   }
 
 #elif defined(XP_MACOSX)