diff --git a/src/git/thread-utils.h b/src/git/thread-utils.h
index bc4153d7a..7322d43c8 100644
--- a/src/git/thread-utils.h
+++ b/src/git/thread-utils.h
@@ -22,8 +22,8 @@
 # define GIT_TLS /* nothing: tls vars are thread-global */
 #endif
 
-/* sparse doesn't grok thread-local variables */
-#if defined(__CHECKER__)
+/* sparse and cygwin don't grok thread-local variables */
+#if defined(__CHECKER__) || defined(__CYGWIN__)
 # undef GIT_HAS_TLS
 # undef GIT_TLS
 # define GIT_TLS