diff --git a/floats/floats.go b/floats/floats.go
index a6ecfcbb..625ade05 100644
--- a/floats/floats.go
+++ b/floats/floats.go
@@ -706,7 +706,7 @@ func Same(s, t []float64) bool {
 	}
 	for i, v := range s {
 		w := t[i]
-		if v != w && !math.IsNaN(v) && !math.IsNaN(w) {
+		if v != w && !(math.IsNaN(v) && math.IsNaN(w)) {
 			return false
 		}
 	}
diff --git a/floats/floats_test.go b/floats/floats_test.go
index a208fea6..e11d2256 100644
--- a/floats/floats_test.go
+++ b/floats/floats_test.go
@@ -1130,7 +1130,7 @@ func TestSame(t *testing.T) {
 	}
 	s1 = []float64{1, 2, math.NaN(), 4}
 	s2 = []float64{1, math.NaN(), 3, 4}
-	if !Same(s1, s2) {
+	if Same(s1, s2) {
 		t.Errorf("Slices with unmatching NaN values returned as equal")
 	}
 }