diff --git a/parser/internal/bytestring/bytestring.go b/parser/internal/bytestring/bytestring.go
index 241bb52..5bcf5bc 100644
--- a/parser/internal/bytestring/bytestring.go
+++ b/parser/internal/bytestring/bytestring.go
@@ -79,7 +79,7 @@ func (s *String) ReadBytes(out *[]byte, n int) bool {
 // ReadCompactSize reads and interprets a Bitcoin-custom compact integer
 // encoding used for length-prefixing and count values. If the values fall
 // outside the expected canonical ranges, it returns false.
-func (s *String) ReadCompactSize(size *uint64) bool {
+func (s *String) ReadCompactSize(size *int) bool {
 	lenBytes := s.read(1)
 	if lenBytes == nil {
 		return false
@@ -116,19 +116,19 @@ func (s *String) ReadCompactSize(size *uint64) bool {
 		return false
 	}
 
-	*size = length
+	*size = int(length)
 	return true
 }
 
 // ReadCompactLengthPrefixed reads data prefixed by a CompactSize-encoded
 // length field into out. It reports whether the read was successful.
 func (s *String) ReadCompactLengthPrefixed(out *String) bool {
-	var length uint64
+	var length int
 	if ok := s.ReadCompactSize(&length); !ok {
 		return false
 	}
 
-	v := s.read(int(length))
+	v := s.read(length)
 	if v == nil {
 		return false
 	}
diff --git a/parser/transaction.go b/parser/transaction.go
index 17296fc..ae10db3 100644
--- a/parser/transaction.go
+++ b/parser/transaction.go
@@ -267,7 +267,7 @@ func (tx *transaction) ParseFromSlice(data []byte) ([]byte, error) {
 		}
 	}
 
-	var txInCount uint64
+	var txInCount int
 	if ok := s.ReadCompactSize(&txInCount); !ok {
 		return nil, errors.New("could not read tx_in_count")
 	}
@@ -288,7 +288,7 @@ func (tx *transaction) ParseFromSlice(data []byte) ([]byte, error) {
 		}
 	}
 
-	var txOutCount uint64
+	var txOutCount int
 	if ok := s.ReadCompactSize(&txOutCount); !ok {
 		return nil, errors.New("could not read tx_out_count")
 	}
@@ -315,12 +315,13 @@ func (tx *transaction) ParseFromSlice(data []byte) ([]byte, error) {
 		}
 	}
 
+	var spendCount, outputCount int
+
 	if tx.version >= 4 {
 		if ok := s.ReadInt64(&tx.valueBalance); !ok {
 			return nil, errors.New("could not read valueBalance")
 		}
 
-		var spendCount uint64
 		if ok := s.ReadCompactSize(&spendCount); !ok {
 			return nil, errors.New("could not read nShieldedSpend")
 		}
@@ -337,7 +338,6 @@ func (tx *transaction) ParseFromSlice(data []byte) ([]byte, error) {
 			}
 		}
 
-		var outputCount uint64
 		if ok := s.ReadCompactSize(&outputCount); !ok {
 			return nil, errors.New("could not read nShieldedOutput")
 		}
@@ -356,7 +356,7 @@ func (tx *transaction) ParseFromSlice(data []byte) ([]byte, error) {
 	}
 
 	if tx.version >= 2 {
-		var joinSplitCount uint64
+		var joinSplitCount int
 		if ok := s.ReadCompactSize(&joinSplitCount); !ok {
 			return nil, errors.New("could not read nJoinSplit")
 		}