diff --git a/Example.Tests/Calculator.fs b/Example.Tests/Calculator.fs
index cfcce3b..030e391 100644
--- a/Example.Tests/Calculator.fs
+++ b/Example.Tests/Calculator.fs
@@ -1,10 +1,4 @@
 namespace Example
 
 module Calculator =
-    let addOne value = value + 1
-
-    let absoluteDifference left right =
-        if left >= right then left - right else right - left
-
-    let isLeapYear year =
-        year % 4 = 0 && (year % 100 <> 0 || year % 400 = 0)
+    let addOne value = value - 1
diff --git a/Example.Tests/CalculatorTests.fs b/Example.Tests/CalculatorTests.fs
index 0a96e10..1555082 100644
--- a/Example.Tests/CalculatorTests.fs
+++ b/Example.Tests/CalculatorTests.fs
@@ -8,20 +8,14 @@ type CalculatorTests() =
     [<Fact>]
     [<MutationCase("""
     diff --git a/Example.Tests/Calculator.fs b/Example.Tests/Calculator.fs
-    index cfcce3b..39be7f3 100644
+    index 6f0c515..030e391 100644
     --- a/Example.Tests/Calculator.fs
     +++ b/Example.Tests/Calculator.fs
-    @@ -1,7 +1,7 @@
+    @@ -1,4 +1,4 @@
      namespace Example
 
      module Calculator =
     -    let addOne value = value + 1
     +    let addOne value = value - 1
-
-         let absoluteDifference left right =
-             if left >= right then left - right else right - left
-
-        member _.AddOne_increments() =
-            Assert.Equal(42, Calculator.addOne 41)
     """)>]
     member _.AddOne_increments() = Assert.Equal(42, Calculator.addOne 41)