diff --git a/doc/examples/tlsauthentication.c b/doc/examples/tlsauthentication.c
index 4d616b6f..f68a686f 100644
--- a/doc/examples/tlsauthentication.c
+++ b/doc/examples/tlsauthentication.c
@@ -98,12 +98,13 @@ load_file (const char *filename)
   if (!fp)
     return NULL;
 
-  buffer = malloc (size);
+  buffer = malloc (size + 1);
   if (!buffer)
     {
       fclose (fp);
       return NULL;
     }
+  buffer[size] = '\0';
 
   if (size != fread (buffer, 1, size, fp))
     {