diff --git a/lib/rules/no-return-and-callback.js b/lib/rules/no-return-and-callback.js
index 7d6a26c..bc1198a 100644
--- a/lib/rules/no-return-and-callback.js
+++ b/lib/rules/no-return-and-callback.js
@@ -13,17 +13,6 @@ function reportIfShortArrowFunction(context, node) {
     return false;
 }
 
-function isExplicitUndefined(node) {
-    return node && node.type === 'Identifier' && node.name === 'undefined';
-}
-
-function isReturnOfUndefined(node) {
-    const argument = node.argument;
-    const isImplicitUndefined = argument === null;
-
-    return isImplicitUndefined || isExplicitUndefined(argument);
-}
-
 function isFunctionCallWithName(node, name) {
     return node.type === 'CallExpression' &&
         node.callee.type === 'Identifier' &&
@@ -33,7 +22,7 @@ function isFunctionCallWithName(node, name) {
 function isAllowedReturnStatement(node, doneName) {
     const argument = node.argument;
 
-    if (isReturnOfUndefined(node) || argument.type === 'Literal') {
+    if (astUtils.isReturnOfUndefined(node) || argument.type === 'Literal') {
         return true;
     }
 
diff --git a/lib/rules/no-return-from-async.js b/lib/rules/no-return-from-async.js
index 750b3ad..9fa453d 100644
--- a/lib/rules/no-return-from-async.js
+++ b/lib/rules/no-return-from-async.js
@@ -13,21 +13,10 @@ function reportIfShortArrowFunction(context, node) {
     return false;
 }
 
-function isExplicitUndefined(node) {
-    return node && node.type === 'Identifier' && node.name === 'undefined';
-}
-
-function isReturnOfUndefined(node) {
-    const argument = node.argument;
-    const isImplicitUndefined = argument === null;
-
-    return isImplicitUndefined || isExplicitUndefined(argument);
-}
-
 function isAllowedReturnStatement(node) {
     const argument = node.argument;
 
-    if (isReturnOfUndefined(node) || argument.type === 'Literal') {
+    if (astUtils.isReturnOfUndefined(node) || argument.type === 'Literal') {
         return true;
     }
 
diff --git a/lib/util/ast.js b/lib/util/ast.js
index e03263b..88d3063 100644
--- a/lib/util/ast.js
+++ b/lib/util/ast.js
@@ -81,6 +81,17 @@ function hasParentMochaFunctionCall(functionExpression) {
     return isTestCase(functionExpression.parent) || isHookCall(functionExpression.parent);
 }
 
+function isExplicitUndefined(node) {
+    return node && node.type === 'Identifier' && node.name === 'undefined';
+}
+
+function isReturnOfUndefined(node) {
+    const argument = node.argument;
+    const isImplicitUndefined = argument === null;
+
+    return isImplicitUndefined || isExplicitUndefined(argument);
+}
+
 const findReturnStatement = R.find(R.propEq('type', 'ReturnStatement'));
 
 module.exports = {
@@ -93,5 +104,6 @@ module.exports = {
     isHookCall,
     isStringLiteral,
     hasParentMochaFunctionCall,
-    findReturnStatement
+    findReturnStatement,
+    isReturnOfUndefined
 };