diff --git a/prefix/bcd.go b/prefix/bcd.go
index 39c3ee29..32df8ac5 100644
--- a/prefix/bcd.go
+++ b/prefix/bcd.go
@@ -72,7 +72,7 @@ type bcdFixedPrefixer struct {
 }
 
 func (p *bcdFixedPrefixer) EncodeLength(fixLen, dataLen int) ([]byte, error) {
-	if dataLen > fixLen {
+	if dataLen != fixLen {
 		return nil, fmt.Errorf("field length: %d should be fixed: %d", dataLen, fixLen)
 	}
 
diff --git a/prefix/bcd_test.go b/prefix/bcd_test.go
index 752f52c7..ee89445f 100644
--- a/prefix/bcd_test.go
+++ b/prefix/bcd_test.go
@@ -84,5 +84,11 @@ func TestBCDFixedPrefixer_EncodeLengthValidation(t *testing.T) {
 
 	_, err := pref.EncodeLength(8, 12)
 
+	require.Error(t, err)
 	require.Contains(t, err.Error(), "field length: 12 should be fixed: 8")
+
+	_, err = pref.EncodeLength(8, 6)
+
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "field length: 6 should be fixed: 8")
 }
diff --git a/prefix/ebcdic.go b/prefix/ebcdic.go
index f8f0b01c..cfe6d3eb 100644
--- a/prefix/ebcdic.go
+++ b/prefix/ebcdic.go
@@ -71,7 +71,7 @@ type ebcdicFixedPrefixer struct {
 }
 
 func (p *ebcdicFixedPrefixer) EncodeLength(fixLen, dataLen int) ([]byte, error) {
-	if dataLen > fixLen {
+	if dataLen != fixLen {
 		return nil, fmt.Errorf("field length: %d should be fixed: %d", dataLen, fixLen)
 	}
 
diff --git a/prefix/ebcdic_test.go b/prefix/ebcdic_test.go
index a157b744..76b42e36 100644
--- a/prefix/ebcdic_test.go
+++ b/prefix/ebcdic_test.go
@@ -84,5 +84,11 @@ func TestEBCDICFixedPrefixer_EncodeLengthValidation(t *testing.T) {
 
 	_, err := pref.EncodeLength(8, 12)
 
+	require.Error(t, err)
 	require.Contains(t, err.Error(), "field length: 12 should be fixed: 8")
+
+	_, err = pref.EncodeLength(8, 6)
+
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "field length: 6 should be fixed: 8")
 }