diff --git a/common.c b/common.c
index 94d5aa4..12e1eff 100644
--- a/common.c
+++ b/common.c
@@ -65,6 +65,12 @@ transform_str (char *s, int (*tolower) (int c))
 		*s = tolower (*s);
 }
 
+static char *
+str_cut_until (const char *s, const char *alphabet)
+{
+	return xstrndup (s, strcspn (s, alphabet));
+}
+
 static void
 split_str (const char *s, char delimiter, struct str_vector *out)
 {
diff --git a/degesch.c b/degesch.c
index 6294316..6e3d6a6 100644
--- a/degesch.c
+++ b/degesch.c
@@ -2139,7 +2139,7 @@ irc_server_strncmp (struct server *s, const char *a, const char *b, size_t n)
 static char *
 irc_cut_nickname (const char *prefix)
 {
-	return xstrndup (prefix, strcspn (prefix, "!@"));
+	return str_cut_until (prefix, "!@");
 }
 
 static const char *
@@ -6251,8 +6251,7 @@ dump_matching_options
 	for (size_t i = 0; i < output->len; i++)
 	{
 		// Yeah, I know
-		const char *line = output->vector[i];
-		char *key = xstrndup (line, strcspn (line, " "));
+		char *key = str_cut_until (output->vector[i], " ");
 		if (fnmatch (mask, key, 0))
 			str_vector_remove (output, i--);
 		free (key);
@@ -6702,7 +6701,7 @@ handle_command_set_assign
 	}
 	for (size_t i = 0; i < all->len; i++)
 	{
-		char *key = xstrndup (all->vector[i], strcspn (all->vector[i], " "));
+		char *key = str_cut_until (all->vector[i], " ");
 		handle_command_set_assign_item (ctx, key, new_, add, remove);
 		free (key);
 	}
@@ -7837,8 +7836,7 @@ complete_option (struct app_context *ctx, struct completion *data,
 	char *mask = xstrdup_printf ("%s*", word);
 	for (size_t i = 0; i < options.len; i++)
 	{
-		const char *line = options.vector[i];
-		char *key = xstrndup (line, strcspn (line, " "));
+		char *key = str_cut_until (options.vector[i], " ");
 		if (!fnmatch (mask, key, 0))
 			str_vector_add_owned (output, key);
 		else