diff --git a/moz.build b/moz.build
index fbec04108cc3c..dd1afd744d855 100644
--- a/moz.build
+++ b/moz.build
@@ -183,7 +183,7 @@ if CONFIG["MOZ_BUILD_APP"]:
 else:
     include("/toolkit/toolkit.mozbuild")
 
-OBJDIR_PP_FILES[".cargo"] += [".cargo/config.in"]
+OBJDIR_PP_FILES[".cargo"] += [CONFIG["MOZ_OVERRIDE_CARGO_CONFIG"] or ".cargo/config.in"]
 
 DEFINES["top_srcdir"] = TOPSRCDIR
 
diff --git a/toolkit/toolkit.mozbuild b/toolkit/toolkit.mozbuild
index d2ccd8748228b..2e3721e8a5807 100644
--- a/toolkit/toolkit.mozbuild
+++ b/toolkit/toolkit.mozbuild
@@ -31,9 +31,10 @@ if CONFIG['ENABLE_TESTS']:
         '/toolkit/library/gtest/rust',
     ]
 
-DIRS += [
-    '/toolkit/library/rust',
-]
+if not CONFIG['MOZ_OVERRIDE_GKRUST']:
+    DIRS += [
+        '/toolkit/library/rust',
+    ]
 
 if CONFIG['MOZ_SANDBOX']:
     DIRS += ['/security/sandbox']