diff --git a/src/runtime/sqrt.go b/src/runtime/sqrt.go
index 7452a61f3c..1b130e3b01 100644
--- a/src/runtime/sqrt.go
+++ b/src/runtime/sqrt.go
@@ -117,7 +117,7 @@ func sqrt(ix uint64) uint64 {
 	// normalize x
 	exp := int((ix >> float64Shift) & float64Mask)
 	if exp == 0 { // subnormal x
-		for ix&1<<float64Shift == 0 {
+		for ix&(1<<float64Shift) == 0 {
 			ix <<= 1
 			exp--
 		}
diff --git a/src/runtime/sqrt_test.go b/src/runtime/sqrt_test.go
index d5ccc7fb1d..54539e1e2e 100644
--- a/src/runtime/sqrt_test.go
+++ b/src/runtime/sqrt_test.go
@@ -74,6 +74,7 @@ var vfsqrtSC = []float64{
 	0,
 	math.Inf(1),
 	math.NaN(),
+	math.Float64frombits(2),
 }
 var sqrtSC = []float64{
 	math.NaN(),
@@ -82,4 +83,5 @@ var sqrtSC = []float64{
 	0,
 	math.Inf(1),
 	math.NaN(),
+	3.1434555694052576e-162,
 }