diff --git a/plugins/external/INTERFACE.md b/plugins/external/INTERFACE.md
index a9ef7c8b0..69c771b60 100644
--- a/plugins/external/INTERFACE.md
+++ b/plugins/external/INTERFACE.md
@@ -73,10 +73,13 @@ External Message Modification Modules
 The external plugin will use stdin to receive the message that it potentially
 can modify. The message will be LF-terminated, and no LF must be present within
 the message itself.  By default, the MSG part of the message is provided as input.
-The "interface.input" parameter can be used to modify this. It currently support
-either "msg" (the default) or "rawmsg", which is the complete message (including
-header) as received by rsyslog. In the future, the value "json" will permit to 
-receive a JSON encoded copy of the message.
+The "interface.input" parameter can be used to modify this. It may has the following
+values:
+
+* "msg" (the default)
+* "rawmsg", which is the complete message (including header) as received by rsyslog
+* "json", which is the complete message object (with all properties broken
+  out) as a JSON object string. This is the "jsonmesg" dynamic message property.
 
 **Note**: if multi-line messages are to be processed, JSON representation **must**
 be used, otherwise errors will happen.
diff --git a/plugins/mmexternal/mmexternal.c b/plugins/mmexternal/mmexternal.c
index a9e882735..149cf6757 100644
--- a/plugins/mmexternal/mmexternal.c
+++ b/plugins/mmexternal/mmexternal.c
@@ -440,16 +440,17 @@ callExtProg(wrkrInstanceData_t *__restrict__ const pWrkrData, msg_t *__restrict_
 	int writeOffset;
 	char errStr[1024];
 	uchar msgStr[4096];
-	uchar *inputstr; /* string to be processed by external program */
+	const uchar *inputstr; /* string to be processed by external program */
 	DEFiRet;
 	
 	if(pWrkrData->pData->inputProp == INPUT_MSG) {
 		inputstr = getMSG(pMsg);
 		lenWrite = getMSGLen(pMsg);
 	} else if(pWrkrData->pData->inputProp == INPUT_RAWMSG) {
-		getRawMsg(pMsg, &inputstr, &lenWrite);
+		getRawMsg(pMsg, (uchar**)&inputstr, &lenWrite);
 	} else  {
-		DBGPRINTF("DDDDD: JSON mode not yet supported!\n");
+		inputstr = msgGetJSONMESG(pMsg);
+		lenWrite = strlen((const char*)inputstr);
 	}
 	lenWrite = snprintf((char*)msgStr, sizeof(msgStr), "%s\n", inputstr); // TODO: make this more solid!
 	writeOffset = 0;
diff --git a/runtime/msg.c b/runtime/msg.c
index d22099e6d..5d18163ae 100644
--- a/runtime/msg.c
+++ b/runtime/msg.c
@@ -1935,8 +1935,8 @@ void MsgSetParseSuccess(msg_t * const pMsg, int bSuccess)
 
 
 /* return full message as a json string */
-static const uchar*
-getJSONMESG(msg_t *__restrict__ const pMsg)
+const uchar*
+msgGetJSONMESG(msg_t *__restrict__ const pMsg)
 {
 	struct json_object *json;
 	struct json_object *jval;
@@ -3044,7 +3044,7 @@ uchar *MsgGetProp(msg_t *__restrict__ const pMsg, struct templateEntry *__restri
 			pRes = (uchar*)getMSGID(pMsg);
 			break;
 		case PROP_JSONMESG:
-			pRes = (uchar*)getJSONMESG(pMsg);
+			pRes = (uchar*)msgGetJSONMESG(pMsg);
 			break;
 #ifdef USE_LIBUUID
 		case PROP_UUID:
diff --git a/runtime/msg.h b/runtime/msg.h
index 87142f808..ec22545f6 100644
--- a/runtime/msg.h
+++ b/runtime/msg.h
@@ -194,6 +194,7 @@ rsRetVal msgAddJSON(msg_t *pM, uchar *name, struct json_object *json);
 rsRetVal MsgGetSeverity(msg_t *pThis, int *piSeverity);
 rsRetVal MsgDeserialize(msg_t *pMsg, strm_t *pStrm);
 rsRetVal MsgSetPropsViaJSON(msg_t *__restrict__ const pMsg, const uchar *__restrict__ const json);
+const uchar* msgGetJSONMESG(msg_t *__restrict__ const pMsg);
 
 /* TODO: remove these five (so far used in action.c) */
 uchar *getMSG(msg_t *pM);