diff --git a/src/cmd/compile/internal/ssa/poset.go b/src/cmd/compile/internal/ssa/poset.go
index 1e04b48ba4..d2719eb8a1 100644
--- a/src/cmd/compile/internal/ssa/poset.go
+++ b/src/cmd/compile/internal/ssa/poset.go
@@ -12,7 +12,7 @@ import (
 // If true, check poset integrity after every mutation
 var debugPoset = false
 
-const uintSize = 32 << (^uint(0) >> 32 & 1) // 32 or 64
+const uintSize = 32 << (^uint(0) >> 63) // 32 or 64
 
 // bitset is a bit array for dense indexes.
 type bitset []uint
diff --git a/src/math/bits/bits.go b/src/math/bits/bits.go
index 879ef2da54..65452feda2 100644
--- a/src/math/bits/bits.go
+++ b/src/math/bits/bits.go
@@ -8,7 +8,7 @@
 // functions for the predeclared unsigned integer types.
 package bits
 
-const uintSize = 32 << (^uint(0) >> 32 & 1) // 32 or 64
+const uintSize = 32 << (^uint(0) >> 63) // 32 or 64
 
 // UintSize is the size of a uint in bits.
 const UintSize = uintSize