diff --git a/src/vim9script.c b/src/vim9script.c
index 24953cd..34c3dab 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -198,11 +198,11 @@
 	char_u	*funcname;
 
 	// it could be a user function.
-	if (STRLEN(name) < sizeof(buffer) - 10)
+	if (STRLEN(name) < sizeof(buffer) - 15)
 	    funcname = buffer;
 	else
 	{
-	    funcname = alloc(STRLEN(name) + 10);
+	    funcname = alloc(STRLEN(name) + 15);
 	    if (funcname == NULL)
 		return -1;
 	}