diff --git a/src/mutex.h b/src/mutex.h
new file mode 100644
index 000000000..a872231b4
--- /dev/null
+++ b/src/mutex.h
@@ -0,0 +1,18 @@
+#include "hamlib/config.h"
+
+#if defined(HAVE_PTHREAD)
+#include <pthread.h>
+#endif
+
+#ifdef HAVE_PTHREAD
+#define MUTEX(var) static pthread_mutex_t var = PTHREAD_MUTEX_INITIALIZER
+#define MUTEX_LOCK(var) pthread_mutex_lock(&var)
+#define MUTEX_UNLOCK(var)  pthread_mutex_unlock(&var)
+#else
+#warning NOT PTHREAD
+#define MUTEX(var)
+#define MUTEX_LOCK(var)
+#define MUTEX_UNLOCK(var)
+#endif
+
+extern int MUTEX_CHECK(pthread_mutex_t *m);
diff --git a/src/rig.c b/src/rig.c
index cc4b24073..26b567485 100644
--- a/src/rig.c
+++ b/src/rig.c
@@ -61,10 +61,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <errno.h>
-#if defined(HAVE_PTHREAD)
-#include <pthread.h>
-#endif
-
+#include "mutex.h"
 
 #include <hamlib/rig.h>
 #include "serial.h"
@@ -174,17 +171,6 @@ const char hamlib_copyright[231] = /* hamlib 1.2 ABI specifies 231 bytes */
 
 #define LOCK(n) if (rig->state.depth == 1) { rig_debug(RIG_DEBUG_CACHE, "%s: %s\n", n?"lock":"unlock", __func__);  rig_lock(rig,n); }
 
-#ifdef HAVE_PTHREAD
-#define MUTEX(var) static pthread_mutex_t var = PTHREAD_MUTEX_INITIALIZER
-#define MUTEX_LOCK(var) pthread_mutex_lock(&var)
-#define MUTEX_UNLOCK(var)  pthread_mutex_unlock(&var)
-#else
-#warning NOT PTHREAD
-#define MUTEX(var)
-#define MUTEX_LOCK(var)
-#define MUTEX_UNLOCK(var)
-#endif
-
 MUTEX(morse_mutex);
 
 #ifdef HAVE_PTHREAD