diff --git a/CMDList/CMDList.c b/CMDList/CMDList.c
index dde5b50..dd89e2b 100644
--- a/CMDList/CMDList.c
+++ b/CMDList/CMDList.c
@@ -31,32 +31,60 @@ int CMDList_deinit(CMDList_t *list)
 // add a command in the command tree
 int CMDList_add(CMDList_t *list, CMD_t* cmd)
 {
-	char* read_p = cmd;
+	int returnCode = 0;
+	char* read_p = cmd->cmd;
 	CMDList_t* list_p = list;
 
+	if (read_p == NULL)
+	{
+		returnCode = -1;
+	}
+
 	while (
-		   (read_p != NULL)
-		&& (*read_p != ' ') // space ends the command
-		&& (*read_p != '\n') // end of line
-		&& (*read_p != '\r') // end of line
-		&& (*read_p != 0) // end of string
-		&& (read_p - (char*)cmd < 500)
+		   ((read_p - cmd->cmd) < (500 * sizeof(char)))
+		&& (returnCode == 0)
 	)
 	{
-		char c = *read_p & (~0x20); // to uppercase
-		if ((*read_p >= 'A') && (*read_p <= 'Z'))
-		{
-			read_p += (*read_p - 'A') * sizeof(CMDList_t*);
-			if (*((CMDList_t**)read_p) == NULL)
-			{
-				read_p = malloc(sizeof(CMDList_t));
+		char c = *read_p & (~0x20); // convert to uppercase
+		if ((c >= 'A') && (c <= 'Z'))
+		{ // valid character
+
+			// get memory address of the caracter in the CMDList
+			list_p += (c - 'A') * sizeof(CMDList_t*);
+
+			if (*((CMDList_t**)list_p) == NULL)
+			{ // it does not point to another list
+				// allocate a new list for it
+				*((CMDList_t**)list_p) = malloc(sizeof(CMDList_t));
+				if (list_p == NULL)
+				{ // allocation faild (memory full?)
+					returnCode = -2;
+				}
 			}
 			else
-			{
-				read_p = *((CMDList_t**)read_p);
+			{ // it points to an other list
+				// update pointer to this list
+				*((CMDList_t**)list_p) = *((CMDList_t**)read_p);
 			}
+			// update list_p for the next list
+			list_p = *((CMDList_t**)list_p);
 		}
+		else
+		{ // invalid caracter
+			break;
+		}
+
+		// read next character
+		read_p += sizeof(char);
 	}
+
+	if (returnCode >= 0)
+	{ // no errors
+		// add command in it's spot
+		list_p->cmd = cmd;
+	}
+
+	return returnCode;
 }
 
 // search command in the tree