diff --git a/libcxx/include/__cxx03/__thread/support/windows.h b/libcxx/include/__cxx03/__thread/support/windows.h
index 45252a57efaec..ee4a74dd1267d 100644
--- a/libcxx/include/__cxx03/__thread/support/windows.h
+++ b/libcxx/include/__cxx03/__thread/support/windows.h
@@ -28,7 +28,8 @@ using __libcpp_timespec_t = ::timespec;
 typedef void* __libcpp_mutex_t;
 #define _LIBCPP_MUTEX_INITIALIZER 0
 
-#if defined(_M_IX86) || defined(__i386__) || defined(_M_ARM) || defined(__arm__)
+#if defined(_M_IX86) || defined(__i386__) || defined(_M_ARM) || defined(__arm__) || defined(_M_MRX000) ||              \
+    defined(__mips__)
 typedef void* __libcpp_recursive_mutex_t[6];
 #elif defined(_M_AMD64) || defined(__x86_64__) || defined(_M_ARM64) || defined(__aarch64__)
 typedef void* __libcpp_recursive_mutex_t[5];
diff --git a/libcxx/include/__thread/support/windows.h b/libcxx/include/__thread/support/windows.h
index 5dc4fa14f45b6..bc06082880427 100644
--- a/libcxx/include/__thread/support/windows.h
+++ b/libcxx/include/__thread/support/windows.h
@@ -28,7 +28,8 @@ using __libcpp_timespec_t = ::timespec;
 typedef void* __libcpp_mutex_t;
 #define _LIBCPP_MUTEX_INITIALIZER 0
 
-#if defined(_M_IX86) || defined(__i386__) || defined(_M_ARM) || defined(__arm__)
+#if defined(_M_IX86) || defined(__i386__) || defined(_M_ARM) || defined(__arm__) || defined(_M_MRX000) ||              \
+    defined(__mips__)
 typedef void* __libcpp_recursive_mutex_t[6];
 #elif defined(_M_AMD64) || defined(__x86_64__) || defined(_M_ARM64) || defined(__aarch64__)
 typedef void* __libcpp_recursive_mutex_t[5];