diff --git a/src/math/sqrt.go b/src/math/sqrt.go
index 7e95f2365b..1077a62897 100644
--- a/src/math/sqrt.go
+++ b/src/math/sqrt.go
@@ -67,7 +67,7 @@ package math
 //
 //      One may easily use induction to prove (4) and (5).
 //      Note. Since the left hand side of (3) contain only i+2 bits,
-//            it does not necessary to do a full (53-bit) comparison
+//            it is not necessary to do a full (53-bit) comparison
 //            in (3).
 //   3. Final rounding
 //      After generating the 53 bits result, we compute one more bit.