diff --git a/tests.scm b/tests.scm
new file mode 100644
index 0000000..17fdfb8
--- /dev/null
+++ b/tests.scm
@@ -0,0 +1,40 @@
+(check 
+ (sha1-hash-string "")
+ => #xda39a3ee5e6b4b0d3255bfef95601890afd80709)
+
+(check 
+ (sha1-hash-string "a")
+ => #x86f7e437faa5a7fce15d1ddcb9eaeaea377667b8)
+
+(check 
+ (sha1-hash-string "abc")
+ => #xa9993e364706816aba3e25717850c26c9cd0d89d)
+
+(check 
+ (sha1-hash-string "message digest")
+ => #xc12252ceda8be8994d5fa0290a47231c1d16aae3)
+
+(check 
+ (sha1-hash-string "abcdefghijklmnopqrstuvwxyz")
+ => #x32d10c7b8cf96570ca04ce37f2a19d84240d3a89)
+
+(check 
+ (sha1-hash-string "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")
+ => #x761c457bf73b14d27e9e9265c46f4b4dda11f940)
+
+(check 
+ (sha1-hash-string "12345678901234567890123456789012345678901234567890123456789012345678901234567890")
+ => #x50abf5706a150990a08b2c5ea40fa0e585554732)
+
+(check 
+ (sha1-hash-string "MD5 has not yet (2001-09-03) been broken, but sufficient attacks have been made that its security is in some doubt")
+ => #x18eca4333979c4181199b7b4fab8786d16cf2846)
+
+(check
+ (sha1-hash-string "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq")
+ => #x84983e441c3bd26ebaae4aa1f95129e5e54670f1)
+
+;;; run this test only if you want to burn many cpu cycles...
+;(check
+; (sha1-hash-string (make-string 1000000 #\a))
+; => #x34aa973cd4c4daa4f61eeb2bdbad27316534016f)