diff --git a/src/iothread.cpp b/src/iothread.cpp
index 746a2dbac..5600a5b19 100644
--- a/src/iothread.cpp
+++ b/src/iothread.cpp
@@ -21,11 +21,17 @@
 #include "global_safety.h"
 #include "wutil.h"
 
+#ifdef PTHREAD_THREADS_MAX
+#if PTHREAD_THREADS_MAX < 64
+#define IO_MAX_THREADS PTHREAD_THREADS_MAX
+#endif
+#else
 #ifdef _POSIX_THREAD_THREADS_MAX
 #if _POSIX_THREAD_THREADS_MAX < 64
 #define IO_MAX_THREADS _POSIX_THREAD_THREADS_MAX
 #endif
 #endif
+#endif
 
 #ifndef IO_MAX_THREADS
 #define IO_MAX_THREADS 64