diff --git a/degesch.c b/degesch.c
index 8f8424a..3edbe15 100644
--- a/degesch.c
+++ b/degesch.c
@@ -7276,7 +7276,16 @@ plugin_config_name (struct plugin *self)
 			begin = p;
 
 	size_t len = strcspn (begin, ".");
-	return len ? xstrndup (begin, len) : NULL;
+	if (!len)
+		return NULL;
+
+	// XXX: we might also allow arbitrary strings as object keys (except dots)
+	//   taking care to use the "" syntax while serializing
+	char *copy = xstrndup (begin, len);
+	for (char *p = copy; *p; p++)
+		if (!config_tokenizer_is_word_char (*p))
+			*p = '_';
+	return copy;
 }
 
 // --- Lua ---------------------------------------------------------------------