diff --git a/utils/utils_jack.cpp b/utils/utils_jack.cpp
index 0f6fb5c6..fab4a924 100644
--- a/utils/utils_jack.cpp
+++ b/utils/utils_jack.cpp
@@ -25,7 +25,7 @@
 #define ALSA_CONTROL_MASTER_VOLUME "DAC"
 
 #define JACK_EXTERNAL_PREFIX     "mod-external"
-#define JACK_EXTERNAL_PREFIX_LEN 9
+#define JACK_EXTERNAL_PREFIX_LEN 12
 
 // --------------------------------------------------------------------------------------------------------