diff --git a/errors.go b/errors.go
index aa9d190d..40b8ef66 100644
--- a/errors.go
+++ b/errors.go
@@ -4,28 +4,26 @@
 
 package fincen
 
-import "fmt"
+import (
+	"fmt"
+)
 
 // NewErrTextLength returns an error that the length of value is invalid
 func NewErrValueInvalid(typeStr string) error {
-	errStr := fmt.Sprintf("The %s has invalid value", typeStr)
-	return fmt.Errorf(errStr)
+	return fmt.Errorf("The %s has invalid value", typeStr)
 }
 
 // NewErrFieldRequired returns an error when a field is required
 func NewErrFieldRequired(typeStr string) error {
-	errStr := fmt.Sprintf("The %s is a required field", typeStr)
-	return fmt.Errorf(errStr)
+	return fmt.Errorf("The %s is a required field", typeStr)
 }
 
 // NewErrFiledOmitted returns an error that the field should be omitted
 func NewErrFiledOmitted(typeStr string) error {
-	errStr := fmt.Sprintf("The %s should be omitted", typeStr)
-	return fmt.Errorf(errStr)
+	return fmt.Errorf("The %s should be omitted", typeStr)
 }
 
 // NewErrMinMaxRange returns an error that the field has min/max element range
 func NewErrMinMaxRange(typeStr string) error {
-	errStr := fmt.Sprintf("The %s has invalid min & max range", typeStr)
-	return fmt.Errorf(errStr)
+	return fmt.Errorf("The %s has invalid min & max range", typeStr)
 }
diff --git a/utils.go b/utils.go
index 449551f1..95a64bc6 100644
--- a/utils.go
+++ b/utils.go
@@ -35,7 +35,12 @@ func NumericStringField(s string, max uint) string {
 	if ln > max {
 		return s[ln-max:]
 	}
-	s = strings.Repeat("0", int(max-ln)) + s
+	rem := max - ln
+	if rem > 1_000_000_000 {
+		return ""
+	} else {
+		s = strings.Repeat("0", int(rem)) + s
+	}
 	return s
 }