diff --git a/src/message.c b/src/message.c
index 91b2fe2..38e6959 100644
--- a/src/message.c
+++ b/src/message.c
@@ -655,7 +655,10 @@
 	}
 
 	if (emsg_assert_fails_used && emsg_assert_fails_msg == NULL)
+	{
 	    emsg_assert_fails_msg = vim_strsave(s);
+	    emsg_assert_fails_lnum = SOURCING_LNUM;
+	}
 
 	// set "v:errmsg", also when using ":silent! cmd"
 	set_vim_var_string(VV_ERRMSG, s, -1);