diff --git a/common/math/integer.go b/common/math/integer.go
index dfcb0aecc4..193d95bec2 100644
--- a/common/math/integer.go
+++ b/common/math/integer.go
@@ -30,7 +30,7 @@ type HexOrDecimal64 uint64
 // It is similar to UnmarshalText, but allows parsing real decimals too, not just
 // quoted decimal strings.
 func (i *HexOrDecimal64) UnmarshalJSON(input []byte) error {
-	if len(input) > 1 && input[0] == '"' {
+	if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
 		input = input[1 : len(input)-1]
 	}
 	return i.UnmarshalText(input)