diff --git a/README.md b/README.md
index 15e4c76..c8e627d 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ cond := abool.New()     // default to false
 cond.Set()              // Sets to true
 cond.IsSet()            // Returns true
 cond.UnSet()            // Sets to false
+cond.IsNotSet()         // Returns true
 cond.SetTo(any)         // Sets to whatever you want
 cond.SetToIf(new, old)  // Sets to `new` only if the Boolean matches the `old`, returns whether succeeded
 cond.Toggle()           // Inverts the boolean then returns the value before inverting
diff --git a/bool.go b/bool.go
index e894dab..d4977a2 100644
--- a/bool.go
+++ b/bool.go
@@ -38,6 +38,11 @@ func (ab *AtomicBool) IsSet() bool {
 	return atomic.LoadInt32((*int32)(ab))&1 == 1
 }
 
+// IsNotSet returns whether the Boolean is false.
+func (ab *AtomicBool) IsNotSet() bool {
+	return !ab.IsSet()
+}
+
 // SetTo sets the boolean with given Boolean.
 func (ab *AtomicBool) SetTo(yes bool) {
 	if yes {
diff --git a/bool_test.go b/bool_test.go
index c35aa16..5469f3a 100644
--- a/bool_test.go
+++ b/bool_test.go
@@ -25,6 +25,10 @@ func TestBool(t *testing.T) {
 		t.Fatal("Empty value of AtomicBool should be false")
 	}
 
+	if v.IsSet() == v.IsNotSet() {
+		t.Fatal("AtomicBool.IsNotSet() should be the opposite of IsSet()")
+	}
+
 	v.Set()
 	if !v.IsSet() {
 		t.Fatal("AtomicBool.Set() failed")
@@ -164,12 +168,18 @@ func TestRace(t *testing.T) {
 }
 
 func ExampleAtomicBool() {
-	cond := New()    // default to false
-	cond.Set()       // set to true
-	cond.IsSet()     // returns true
-	cond.UnSet()     // set to false
-	cond.SetTo(true) // set to whatever you want
-	cond.Toggle()    // toggles the boolean value
+	cond := New() // default to false
+	any := true
+	old := any
+	new := !any
+
+	cond.Set()             // Sets to true
+	cond.IsSet()           // Returns true
+	cond.UnSet()           // Sets to false
+	cond.IsNotSet()        // Returns true
+	cond.SetTo(any)        // Sets to whatever you want
+	cond.SetToIf(new, old) // Sets to `new` only if the Boolean matches the `old`, returns whether succeeded
+	cond.Toggle()          // Inverts the boolean then returns the value before inverting
 }
 
 // Benchmark Read