diff --git a/include/mimalloc/internal.h b/include/mimalloc/internal.h
index 791eeb99..3ee20151 100644
--- a/include/mimalloc/internal.h
+++ b/include/mimalloc/internal.h
@@ -50,6 +50,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #define mi_decl_externc
 #endif
 
+// pthreads
 #if !defined(_WIN32) && !defined(__wasi__)
 #define  MI_USE_PTHREADS
 #include <pthread.h>