diff --git a/dom/base/Navigator.cpp b/dom/base/Navigator.cpp
index 30401118b8..ef8a453742 100644
--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -1408,9 +1408,8 @@ Navigator::GetPlatform(nsAString& aPlatform, bool aUsePrefOverriddenValue)
   aPlatform.AssignLiteral("Win32");
 #elif defined(XP_MACOSX) && defined(__ppc__)
   aPlatform.AssignLiteral("MacPPC");
-#elif defined(XP_MACOSX) && defined(__i386__)
-  aPlatform.AssignLiteral("MacIntel");
-#elif defined(XP_MACOSX) && defined(__x86_64__)
+#elif defined(XP_MACOSX)
+  // Always return "MacIntel", even on ARM64 macOS like Safari does.
   aPlatform.AssignLiteral("MacIntel");
 #else
   // XXX Communicator uses compiled-in build-time string defines
diff --git a/netwerk/protocol/http/nsHttpHandler.cpp b/netwerk/protocol/http/nsHttpHandler.cpp
index 880d157a47..a1ba6d3634 100644
--- a/netwerk/protocol/http/nsHttpHandler.cpp
+++ b/netwerk/protocol/http/nsHttpHandler.cpp
@@ -825,6 +825,15 @@ nsHttpHandler::InitUserAgentComponents()
             PR_smprintf_free(buf);
         }
     }
+#elif defined (XP_MACOSX)
+#if defined(__ppc__)
+    mOscpu.AssignLiteral("PPC Mac OS X");
+#else
+    mOscpu.AssignLiteral("Intel Mac OS X");
+#endif
+    SInt32 majorVersion = nsCocoaFeatures::macOSVersionMajor();
+    SInt32 minorVersion = nsCocoaFeatures::macOSVersionMinor();
+    mOscpu += nsPrintfCString(" %d.%d", majorVersion, minorVersion);
 #elif defined (XP_UNIX)
     struct utsname name;