diff --git a/src/transaction_builder.js b/src/transaction_builder.js
index e5e4b2c..b33814b 100644
--- a/src/transaction_builder.js
+++ b/src/transaction_builder.js
@@ -297,7 +297,7 @@ function prepareInput (input, kpPubKey, redeemScript, witnessValue, witnessScrip
     if (!redeemScript.equals(btemplates.witnessScriptHash.output.encode(witnessScriptHash))) throw new Error('Witness script inconsistent with redeem script')
 
     expanded = expandOutput(witnessScript, undefined, kpPubKey)
-    if (!expanded.pubKeys) throw new Error('WitnessScript not supported "' + bscript.toASM(redeemScript) + '"')
+    if (!expanded.pubKeys) throw new Error(expanded.scriptType + ' not supported as witnessScript (' + bscript.toASM(witnessScript) + ')')
 
     prevOutType = btemplates.types.P2SH
     prevOutScript = btemplates.scriptHash.output.encode(redeemScriptHash)
@@ -310,7 +310,7 @@ function prepareInput (input, kpPubKey, redeemScript, witnessValue, witnessScrip
     checkP2SHInput(input, redeemScriptHash)
 
     expanded = expandOutput(redeemScript, undefined, kpPubKey)
-    if (!expanded.pubKeys) throw new Error(expanded.scriptType + ' not supported as redeemScript (' + bscript.toASM(witnessScript) + ')')
+    if (!expanded.pubKeys) throw new Error(expanded.scriptType + ' not supported as redeemScript (' + bscript.toASM(redeemScript) + ')')
 
     prevOutType = btemplates.types.P2SH
     prevOutScript = btemplates.scriptHash.output.encode(redeemScriptHash)
diff --git a/test/fixtures/transaction_builder.json b/test/fixtures/transaction_builder.json
index 93e135d..1475c97 100644
--- a/test/fixtures/transaction_builder.json
+++ b/test/fixtures/transaction_builder.json
@@ -1974,7 +1974,7 @@
         ]
       },
       {
-        "exception": "RedeemScript not supported \"OP_RETURN 06deadbeef03f895a2ad89fb6d696497af486cb7c644a27aa568c7a18dd06113401115185474\"",
+        "exception": "nulldata not supported as redeemScript \\(OP_RETURN 06deadbeef03f895a2ad89fb6d696497af486cb7c644a27aa568c7a18dd06113401115185474\\)",
         "inputs": [
           {
             "txId": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
@@ -2117,7 +2117,7 @@
         ]
       },
       {
-        "exception": "RedeemScript not supported \"OP_HASH160 7f67f0521934a57d3039f77f9f32cf313f3ac74b OP_EQUAL\"",
+        "exception": "scripthash not supported as redeemScript \\(OP_HASH160 7f67f0521934a57d3039f77f9f32cf313f3ac74b OP_EQUAL\\)",
         "inputs": [
           {
             "txId": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",