diff --git a/src/message.c b/src/message.c
index 38e6959..a9851ef 100644
--- a/src/message.c
+++ b/src/message.c
@@ -658,6 +658,9 @@
 	{
 	    emsg_assert_fails_msg = vim_strsave(s);
 	    emsg_assert_fails_lnum = SOURCING_LNUM;
+	    vim_free(emsg_assert_fails_context);
+	    emsg_assert_fails_context = vim_strsave(
+			 SOURCING_NAME == NULL ? (char_u *)"" : SOURCING_NAME);
 	}
 
 	// set "v:errmsg", also when using ":silent! cmd"