diff --git a/src/vim9execute.c b/src/vim9execute.c
index b194e6a..87f3c42 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -1497,9 +1497,11 @@
 	ga_init2(&ga, sizeof(char_u *), 10);
 	for (lnum = iptr->isn_lnum; lnum < end_lnum; ++lnum)
 	{
-	    char_u *p = skipwhite(
-			       ((char_u **)ufunc->uf_lines.ga_data)[lnum - 1]);
+	    char_u *p = ((char_u **)ufunc->uf_lines.ga_data)[lnum - 1];
 
+	    if (p == NULL)
+		continue;  // left over from continuation line
+	    p = skipwhite(p);
 	    if (*p == '#')
 		break;
 	    if (ga_grow(&ga, 1) == OK)