diff --git a/lib/serialize/blocks.js b/lib/serialize/blocks.js
index e525c682..e95003a6 100644
--- a/lib/serialize/blocks.js
+++ b/lib/serialize/blocks.js
@@ -190,15 +190,17 @@ module.exports = {
 		let numInternalOnlyFunctions = 0;
 		if (numLocalFunctions > 0) {
 			const internalFunctions = new Set();
-			for (const {name: paramName, fnDef, fnRecords} of params) {
+			for (const param of params) {
+				const {fnDef} = param;
 				if (!fnDef) continue;
 
 				// Record param name containing this function in function def object
-				(fnDef.internalScopeParamNames || (fnDef.internalScopeParamNames = [])).push(paramName);
+				(fnDef.internalScopeParams || (fnDef.internalScopeParams = [])).push(param);
 
 				// Delete values for this param from all scopes.
 				// Delete the dependencies created between scope record and value record for all scopes.
-				for (const fnRecord of fnRecords) {
+				const paramName = param.name;
+				for (const fnRecord of param.fnRecords) {
 					const {scope} = fnRecord;
 					scope.values[paramName] = undefined;
 
@@ -381,7 +383,7 @@ module.exports = {
 		for (const blockFunction of blockFunctions) {
 			const {
 				scopes: fnScopes, externalVars, internalVars, globalVarNames: fnGlobalVarNames,
-				containsEval: fnContainsEval, isStrict, internalScopeParamNames, isScopeInternalOnly
+				containsEval: fnContainsEval, isStrict, internalScopeParams, isScopeInternalOnly
 			} = blockFunction;
 
 			if (!isScopeInternalOnly) {
@@ -425,7 +427,7 @@ module.exports = {
 					// Replace placeholder var with reference to scope var
 					const fnNodeWithWrapper = fnRecord.node,
 						wrapperParentNode = getNodeWithinWrapperParent(fnNodeWithWrapper);
-					if (!internalScopeParamNames) {
+					if (!internalScopeParams) {
 						// Replace placeholder var with reference to scope var
 						if (wrapperParentNode) {
 							wrapperParentNode[0] = fnNode;
@@ -532,13 +534,13 @@ module.exports = {
 			}
 
 			// If param is a locally-defined function, add `x = ...` to node
-			if (internalScopeParamNames) {
+			if (internalScopeParams) {
 				// If unnamed function, wrap in `(0, ...)` to prevent implicit naming
 				if (!node.id) node = t.sequenceExpression([t.numericLiteral(0), node]);
 
-				for (const paramName of internalScopeParamNames) {
-					const varNode = t.identifier(paramName);
-					paramsByName[paramName].localVarNodes.push(varNode);
+				for (const param of internalScopeParams) {
+					const varNode = t.identifier(param.name);
+					param.localVarNodes.push(varNode);
 					node = t.assignmentExpression('=', varNode, node);
 				}
 			}
diff --git a/lib/serialize/functions.js b/lib/serialize/functions.js
index dddb1c5b..fb7d3efa 100644
--- a/lib/serialize/functions.js
+++ b/lib/serialize/functions.js
@@ -109,7 +109,7 @@ module.exports = {
 
 			fnDef.scopes = new Map(); // Keyed by scope object, value of each is function instance's record
 			fnDef.virtualBlock = undefined;
-			fnDef.internalScopeParamNames = undefined; // May be set in `processBlock()`
+			fnDef.internalScopeParams = undefined; // May be set in `processBlock()`
 			fnDef.isScopeInternalOnly = false; // May be set in `processBlock()`
 
 			functions.set(fnId, fnDef);