X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fstr.c;h=0a9d0d0f26d713fb64ce6de6b0e3f4cfa0a13377;hb=fcb9e49b2a2d57af7c001ae5d2eda9ac443ba36b;hp=4bf2d60c67f1578629abe5cc56771b1d819b1b14;hpb=4944c86a9318bc5b5578ab145a95c116ffd2c9fd;p=pspp

diff --git a/src/str.c b/src/str.c
index 4bf2d60c67..0a9d0d0f26 100644
--- a/src/str.c
+++ b/src/str.c
@@ -331,7 +331,11 @@ ds_end (const struct string *st)
 void
 ds_concat (struct string *st, const char *s)
 {
-  size_t s_len = strlen (s);
+  size_t s_len;
+
+  if (!s) return;
+
+  s_len = strlen (s);
   ds_extend (st, st->length + s_len);
   strcpy (st->string + st->length, s);
   st->length += s_len;