diff --git a/src/libsodium/randombytes/internal/randombytes_internal_random.c b/src/libsodium/randombytes/internal/randombytes_internal_random.c
index f0794f80ac..1176cd6677 100644
--- a/src/libsodium/randombytes/internal/randombytes_internal_random.c
+++ b/src/libsodium/randombytes/internal/randombytes_internal_random.c
@@ -93,6 +93,10 @@ BOOLEAN NTAPI RtlGenRandom(PVOID RandomBuffer, ULONG RandomBufferLength);
 # endif
 #endif
 
+#if !defined(TLS) && !defined(__STDC_NO_THREADS__) && \
+    defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+# define TLS _Thread_local
+#endif
 #ifndef TLS
 # ifdef _WIN32
 #  define TLS __declspec(thread)