diff --git a/src/hci_event_builder.c b/src/hci_event_builder.c
index 0a1ee1310..20ba8be4b 100644
--- a/src/hci_event_builder.c
+++ b/src/hci_event_builder.c
@@ -122,8 +122,11 @@ void hci_event_builder_add_con_handle(hci_event_builder_context_t * context, hci
 void hci_event_builder_add_string(hci_event_builder_context_t * context, const char * text){
     uint16_t length = (uint16_t) strlen(text);
     uint16_t pos = context->pos;
-    hci_event_builder_increment_pos(context, length);
+    hci_event_builder_increment_pos(context, length + 2);
+    context->buffer[pos++] = length;
     memcpy(&context->buffer[pos], text, length);
+    pos += length;
+    context->buffer[pos] = 0;
 }
 
 void hci_event_builder_add_bytes(hci_event_builder_context_t * context, const uint8_t * data, uint16_t length){
diff --git a/src/hci_event_builder.h b/src/hci_event_builder.h
index f0872d81f..248d72c9b 100644
--- a/src/hci_event_builder.h
+++ b/src/hci_event_builder.h
@@ -141,7 +141,7 @@ void hci_event_builder_add_bd_addr(hci_event_builder_context_t * context, bd_add
 void hci_event_builder_add_con_handle(hci_event_builder_context_t * context, hci_con_handle_t con_handle);
 
 /**
- * @bbrief Add string to event
+ * @bbrief Add string to event using JV format: len, string, trailing zero
  * @param context
  * @param value
  */