diff --git a/haskell-math.cabal b/haskell-math.cabal
index 4188dfd..c98af7b 100644
--- a/haskell-math.cabal
+++ b/haskell-math.cabal
@@ -59,6 +59,7 @@ test-suite haskell-math-test
     main-is:          Main.hs
     other-modules:
         GF2test
+        TonelliShanksTest
     build-depends:
         base ^>=4.18.2.1,
         haskell-math,
diff --git a/test/Main.hs b/test/Main.hs
index 2b8ee0d..8b117f9 100644
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -1,10 +1,12 @@
 module Main (main) where
 
 import GF2test (run)
+import TonelliShanksTest (run)
 
 main :: IO ()
 main = do
     putStrLn "Running all tests"
     GF2test.run
+    TonelliShanksTest.run
     putStrLn "All tests done."
 
diff --git a/test/TonelliShanksTest.hs b/test/TonelliShanksTest.hs
new file mode 100644
index 0000000..7ea07be
--- /dev/null
+++ b/test/TonelliShanksTest.hs
@@ -0,0 +1,26 @@
+module TonelliShanksTest (run) where
+
+import Test.HUnit
+
+import ModularSquareRoot (tonelliShanks)
+
+assertOneOf :: (Eq a, Show a) => String -> Maybe a -> [a] -> Assertion
+assertOneOf msg result expected =
+    case result of
+        Nothing -> assertFailure (msg ++ ": expected one of " ++ show expected ++ ", got Nothing")
+        Just x -> assertBool
+                    (msg ++ ": got " ++ show x ++ ", expected one of " ++ show expected)
+                    (x `elem` expected)
+
+run :: IO ()
+run = do
+    putStrLn "Tonelli Shanks test"
+
+    assertOneOf "sqrt(1) mod 7" (tonelliShanks 1 7) [1,6]
+    assertOneOf "sqrt(2) mod 7" (tonelliShanks 2 7) [3,4]
+    assertEqual "sqrt(3) mod 7" (tonelliShanks 3 7) Nothing
+    assertOneOf "sqrt(4) mod 7" (tonelliShanks 4 7) [2,5]
+    assertEqual "sqrt(5) mod 7" (tonelliShanks 5 7) Nothing
+    assertEqual "sqrt(6) mod 7" (tonelliShanks 6 7) Nothing
+
+    putStrLn "Tonelli Shanks test Done."