diff --git a/master/globals.h b/master/globals.h
index 09287783..250a9f38 100644
--- a/master/globals.h
+++ b/master/globals.h
@@ -66,7 +66,7 @@
 #define EC_WAIT_SDO_DICT 3
 
 /** minimum size of a buffer used with ec_state_string() */
-#define EC_STATE_STRING_SIZE 30
+#define EC_STATE_STRING_SIZE 32
 
 /******************************************************************************
  *  EtherCAT protocol
diff --git a/master/module.c b/master/module.c
index 9f115684..7083cb0c 100644
--- a/master/module.c
+++ b/master/module.c
@@ -265,8 +265,8 @@ size_t ec_state_string(uint8_t states, /**< slave states */
         off += sprintf(buffer + off, "OP");
     }
     if (states & EC_SLAVE_STATE_ACK_ERR) {
-        if (!first) off += sprintf(buffer + off, ", ");
-        off += sprintf(buffer + off, "ERR");
+        if (!first) off += sprintf(buffer + off, " + ");
+        off += sprintf(buffer + off, "ERROR");
     }
 
     return off;