diff --git a/test/cctest/test-lockers.cc b/test/cctest/test-lockers.cc
index 77841b5a7f..53ea210899 100644
--- a/test/cctest/test-lockers.cc
+++ b/test/cctest/test-lockers.cc
@@ -674,7 +674,7 @@ class IsolateGenesisThread : public JoinableThread {
 // Test installing extensions in separate isolates concurrently.
 // http://code.google.com/p/v8/issues/detail?id=1821
 TEST(ExtensionsRegistration) {
-#ifdef V8_TARGET_ARCH_ARM
+#if defined V8_TARGET_ARCH_ARM || defined V8_HOST_ARCH_MIPS
   const int kNThreads = 10;
 #else
   const int kNThreads = 40;