diff --git a/include/cryb/test.h b/include/cryb/test.h
index 1138941..77f02e7 100644
--- a/include/cryb/test.h
+++ b/include/cryb/test.h
@@ -86,6 +86,7 @@ int t_is_null(const void *);
 int t_is_not_null(const void *);
 int t_compare_mem(const void *, const void *, size_t);
 int t_compare_str(const char *, const char *);
+int t_compare_strn(const char *, const char *, size_t);
 #define t_compare_num(n, t) int t_compare_##n(t, t);
 t_compare_num(i, int);
 t_compare_num(u, unsigned int);
diff --git a/lib/test/t_util.c b/lib/test/t_util.c
index 025cdeb..8da5102 100644
--- a/lib/test/t_util.c
+++ b/lib/test/t_util.c
@@ -102,6 +102,22 @@ t_compare_str(const char *expected, const char *received)
 	return (1);
 }
 
+/*
+ * Compare two strings up to a specific length, and print a verbose
+ * message if they differ.
+ */
+int
+t_compare_strn(const char *expected, const char *received, size_t len)
+{
+
+	if (strncmp(expected, received, len) != 0) {
+		t_verbose("expected %.*s\n", (int)len, expected);
+		t_verbose("received %.*s\n", (int)len, received);
+		return (0);
+	}
+	return (1);
+}
+
 /*
  * Compare two numbers, and print a verbose message if they differ.
  */