diff --git a/deps/jemalloc-win/include/jemalloc/internal/mutex.h b/deps/jemalloc-win/include/jemalloc/internal/mutex.h
index 8924b3eb926e85d483842af85d10ced764eb1754..53becced601957bf2ceeed10093fad8edbe1d0ab 100644
--- a/deps/jemalloc-win/include/jemalloc/internal/mutex.h
+++ b/deps/jemalloc-win/include/jemalloc/internal/mutex.h
@@ -45,7 +45,7 @@ struct malloc_mutex_s {
 extern bool isthreaded;
 #else
 #  undef isthreaded /* Undo private_namespace.h definition. */
-#  define isthreaded false
+#  define isthreaded true
 #endif
 
 bool    malloc_mutex_init(malloc_mutex_t *mutex);