diff --git a/lib/krb5/heim_threads.h b/lib/krb5/heim_threads.h
index 0f5fa0e02..a4d2de892 100644
--- a/lib/krb5/heim_threads.h
+++ b/lib/krb5/heim_threads.h
@@ -58,7 +58,7 @@
 
 #define HEIMDAL_MUTEX mutex_t
 #define HEIMDAL_MUTEX_INITIALIZER MUTEX_INITIALIZER
-#define HEIMDAL_MUTEX_init(m) mutex_init(m)
+#define HEIMDAL_MUTEX_init(m) mutex_init(m, NULL)
 #define HEIMDAL_MUTEX_lock(m) mutex_lock(m)
 #define HEIMDAL_MUTEX_unlock(m) mutex_unlock(m)
 #define HEIMDAL_MUTEX_destroy(m) mutex_destroy(m)
@@ -70,7 +70,7 @@
 
 #define HEIMDAL_MUTEX pthread_mutex_t
 #define HEIMDAL_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
-#define HEIMDAL_MUTEX_init(m) pthread_mutex_init(m)
+#define HEIMDAL_MUTEX_init(m) pthread_mutex_init(m, NULL)
 #define HEIMDAL_MUTEX_lock(m) pthread_mutex_lock(m)
 #define HEIMDAL_MUTEX_unlock(m) pthread_mutex_unlock(m)
 #define HEIMDAL_MUTEX_destroy(m) pthread_mutex_destroy(m)