diff --git a/ecmc_plugin_socketcan/ecmc_plugin_socketcanApp/src/ecmcCANOpenSDO.cpp b/ecmc_plugin_socketcan/ecmc_plugin_socketcanApp/src/ecmcCANOpenSDO.cpp
index cbe024f..b46c949 100644
--- a/ecmc_plugin_socketcan/ecmc_plugin_socketcanApp/src/ecmcCANOpenSDO.cpp
+++ b/ecmc_plugin_socketcan/ecmc_plugin_socketcanApp/src/ecmcCANOpenSDO.cpp
@@ -539,13 +539,15 @@ int ecmcCANOpenSDO::writeValue() {
 int ecmcCANOpenSDO::tryLockSdo1() {
   epicsMutexLock(getLockMutex_);
   if(busy_) {
+    epicsMutexUnlock(getLockMutex_);
     return 0;
   }
 
   bool prevLock = ptrSdo1Lock_->test_and_set();
   if(prevLock) {
     // wait for busy to go down
-   return 0;
+    epicsMutexUnlock(getLockMutex_);
+    return 0;
   }
 
   busy_ = true;