diff --git a/lib/thread_mosq.c b/lib/thread_mosq.c
index b05c1d2a..46e19807 100644
--- a/lib/thread_mosq.c
+++ b/lib/thread_mosq.c
@@ -20,11 +20,13 @@ Contributors:
 #include <time.h>
 #endif
 
+#if defined(WITH_THREADING)
 #if defined(__linux__) || defined(__NetBSD__)
 #  include <pthread.h>
 #elif defined(__FreeBSD__) || defined(__OpenBSD__)
 #  include <pthread_np.h>
 #endif
+#endif
 
 #include "mosquitto_internal.h"
 #include "net_mosq.h"