diff --git a/error.go b/error.go
index 26071c97..94a5e8ae 100644
--- a/error.go
+++ b/error.go
@@ -151,6 +151,17 @@ const (
 	// coinbase transaction for version 2 and higher blocks does not match
 	// the expected value.
 	ErrBadCoinbaseHeight
+
+	// ErrScriptMalformed indicates a transaction script is malformed in
+	// some way.  For example, it might be longer than the maximum allowed
+	// length or fail to parse.
+	ErrScriptMalformed
+
+	// ErrScriptValidation indicates the result of executing transaction
+	// script failed.  The error covers any failure when executing scripts
+	// such signature verification failures and execution past the end of
+	// the stack.
+	ErrScriptValidation
 )
 
 // Map of ErrorCode values back to their constant names for pretty printing.
@@ -187,6 +198,8 @@ var errorCodeStrings = map[ErrorCode]string{
 	ErrBadCoinbaseValue:      "ErrBadCoinbaseValue",
 	ErrMissingCoinbaseHeight: "ErrMissingCoinbaseHeight",
 	ErrBadCoinbaseHeight:     "ErrBadCoinbaseHeight",
+	ErrScriptMalformed:       "ErrScriptMalformed",
+	ErrScriptValidation:      "ErrScriptValidation",
 }
 
 // String returns the ErrorCode as a human-readable name.
diff --git a/error_test.go b/error_test.go
index d1801d8f..37bfade8 100644
--- a/error_test.go
+++ b/error_test.go
@@ -48,6 +48,8 @@ func TestErrorCodeStringer(t *testing.T) {
 		{btcchain.ErrBadCoinbaseValue, "ErrBadCoinbaseValue"},
 		{btcchain.ErrMissingCoinbaseHeight, "ErrMissingCoinbaseHeight"},
 		{btcchain.ErrBadCoinbaseHeight, "ErrBadCoinbaseHeight"},
+		{btcchain.ErrScriptMalformed, "ErrScriptMalformed"},
+		{btcchain.ErrScriptValidation, "ErrScriptValidation"},
 		{0xffff, "Unknown ErrorCode (65535)"},
 	}
 
diff --git a/scriptval.go b/scriptval.go
index f3badf19..1e300eba 100644
--- a/scriptval.go
+++ b/scriptval.go
@@ -51,15 +51,15 @@ out:
 		select {
 		case txVI := <-v.validateChan:
 			// Ensure the referenced input transaction is available.
-			//txIn := txVI.tx.MsgTx().TxIn[txVI.txInIdx]
 			txIn := txVI.txIn
-			txInHash := &txIn.PreviousOutpoint.Hash
-			originTx, exists := v.txStore[*txInHash]
+			originTxHash := &txIn.PreviousOutpoint.Hash
+			originTx, exists := v.txStore[*originTxHash]
 			if !exists || originTx.Err != nil || originTx.Tx == nil {
-				err := fmt.Errorf("unable to find input "+
+				str := fmt.Sprintf("unable to find input "+
 					"transaction %v referenced from "+
-					"transaction %v", txInHash,
+					"transaction %v", originTxHash,
 					txVI.tx.Sha())
+				err := ruleError(ErrMissingTx, str)
 				v.sendResult(err)
 				break out
 			}
@@ -69,10 +69,12 @@ out:
 			// is available.
 			originTxIndex := txIn.PreviousOutpoint.Index
 			if originTxIndex >= uint32(len(originMsgTx.TxOut)) {
-				err := fmt.Errorf("out of bounds "+
+				str := fmt.Sprintf("out of bounds "+
 					"input index %d in transaction %v "+
 					"referenced from transaction %v",
-					originTxIndex, txInHash, txVI.tx.Sha())
+					originTxIndex, originTxHash,
+					txVI.tx.Sha())
+				err := ruleError(ErrBadTxInput, str)
 				v.sendResult(err)
 				break out
 			}
@@ -83,17 +85,26 @@ out:
 			engine, err := btcscript.NewScript(sigScript, pkScript,
 				txVI.txInIndex, txVI.tx.MsgTx(), v.flags)
 			if err != nil {
+				str := fmt.Sprintf("failed to parse input "+
+					"%s:%d which references output %s:%d - "+
+					"%v (input script bytes %x, prev output "+
+					"script bytes %x)", txVI.tx.Sha(),
+					txVI.txInIndex, originTxHash,
+					originTxIndex, err, sigScript, pkScript)
+				err := ruleError(ErrScriptMalformed, str)
 				v.sendResult(err)
 				break out
 			}
 
 			// Execute the script pair.
 			if err := engine.Execute(); err != nil {
-				err := fmt.Errorf("validate of input "+
-					"%d from transaction %s failed: %v "+
-					"(input script bytes %x, prev output "+
-					"script bytes %x)", txVI.txInIndex,
-					txInHash, err, sigScript, pkScript)
+				str := fmt.Sprintf("failed to validate input "+
+					"%s:%d which references output %s:%d - "+
+					"%v (input script bytes %x, prev output "+
+					"script bytes %x)", txVI.tx.Sha(),
+					txVI.txInIndex, originTxHash,
+					originTxIndex, err, sigScript, pkScript)
+				err := ruleError(ErrScriptValidation, str)
 				v.sendResult(err)
 				break out
 			}