diff --git a/src/config/conf.c b/src/config/conf.c
index ec3205126..3376e69da 100644
--- a/src/config/conf.c
+++ b/src/config/conf.c
@@ -767,7 +767,7 @@ create_config_string(unsigned char *prefix, unsigned char *name,
 	smart_config_string(&tmpstring, 2, i18n, options->value.tree, NULL, 0,
 			    smart_config_output_fn);
 	if (tmpstring.length > origlen)
-		add_bytes_to_string(&config, tmpstring.source, tmpstring.length);
+		add_string_to_string(&config, &tmpstring);
 	done_string(&tmpstring);
 
 	if (!init_string(&tmpstring)) goto get_me_out;
@@ -778,7 +778,7 @@ create_config_string(unsigned char *prefix, unsigned char *name,
 	origlen = tmpstring.length;
 	bind_config_string(&tmpstring);
 	if (tmpstring.length > origlen)
-		add_bytes_to_string(&config, tmpstring.source, tmpstring.length);
+		add_string_to_string(&config, &tmpstring);
 	done_string(&tmpstring);
 
 get_me_out:
diff --git a/src/protocol/common.c b/src/protocol/common.c
index d22fd84b1..41807e132 100644
--- a/src/protocol/common.c
+++ b/src/protocol/common.c
@@ -65,10 +65,8 @@ init_directory_listing(struct string *page, struct uri *uri)
 	    && !add_char_to_string(&dirpath, local ? CHAR_DIR_SEP : '/'))
 		goto out_of_memory;
 
-	/* Decode uri for displaying.  Do not use
-	 * add_string_to_string, because it for some reason returns
-	 * NULL if the second string is empty.  */
-	if (!add_bytes_to_string(&decoded, dirpath.source, dirpath.length))
+	/* Decode uri for displaying.  */
+	if (!add_string_to_string(&decoded, &dirpath))
 		goto out_of_memory;
 	decode_uri_string(&decoded);
 
diff --git a/src/terminal/screen.c b/src/terminal/screen.c
index f0f096ff6..70d96165f 100644
--- a/src/terminal/screen.c
+++ b/src/terminal/screen.c
@@ -73,6 +73,7 @@ static const unsigned char frame_restrict[48] = {
 
 #define TERM_STRING(str) INIT_STRING(str, sizeof(str) - 1)
 
+/* Like add_string_to_string but has fewer checks to slow it down.  */
 #define add_term_string(str, tstr) \
 	add_bytes_to_string(str, (tstr).source, (tstr).length)