diff --git a/src/lxc/cgroups/cgmanager.c b/src/lxc/cgroups/cgmanager.c
index 054eb1715..e8ef8c66c 100644
--- a/src/lxc/cgroups/cgmanager.c
+++ b/src/lxc/cgroups/cgmanager.c
@@ -88,7 +88,8 @@ static void unlock_mutex(pthread_mutex_t *l)
 	int ret;
 
 	if ((ret = pthread_mutex_unlock(l)) != 0) {
-		fprintf(stderr, "pthread_mutex_unlock returned:%d %s\n", ret, strerror(ret));
+		fprintf(stderr, "%s: pthread_mutex_unlock returned:%d %s\n",
+				__FILE__, ret, strerror(ret));
 		exit(1);
 	}
 }
diff --git a/src/lxc/lxclock.c b/src/lxc/lxclock.c
index c85a8461c..dee5aa5f0 100644
--- a/src/lxc/lxclock.c
+++ b/src/lxc/lxclock.c
@@ -84,7 +84,8 @@ static void unlock_mutex(pthread_mutex_t *l)
 	int ret;
 
 	if ((ret = pthread_mutex_unlock(l)) != 0) {
-		fprintf(stderr, "pthread_mutex_unlock returned:%d %s\n", ret, strerror(ret));
+		fprintf(stderr, "%s: pthread_mutex_unlock returned:%d %s\n",
+				__FILE__, ret, strerror(ret));
 		dump_stacktrace();
 		exit(EXIT_FAILURE);
 	}