diff --git a/t/strings.t b/t/strings.t
index 2587cf1..9dbfdb7 100644
--- a/t/strings.t
+++ b/t/strings.t
@@ -1 +1,9 @@
-(expect "hello has 5 letters" (= (length "hello") 5))
+(expect "length of string" (= (length "hello") 5))
+
+(expect "string-upcase" (string= (string-upcase "helLo") "HELLO"))
+
+(expect "string-downcase" (string= (string-downcase "HEllO") "hello"))
+
+(expect "string-capitalize"
+        (string= (string-capitalize "hello world i like cheese")
+                 "Hello World I Like Cheese"))