diff --git a/common/math/exp.go b/common/math/exp.go
index bd6eeb031..3fd31bd76 100644
--- a/common/math/exp.go
+++ b/common/math/exp.go
@@ -7,7 +7,7 @@ import (
 )
 
 // wordSize is the size number of bits in a big.Int Word.
-const wordSize = 32 << (uint64(^big.Word(0))>>63)
+const wordSize = 32 << (uint64(^big.Word(0)) >> 63)
 
 // Exp implement exponentiation by squaring algorithm.
 //