diff --git a/src/CompletionProvider.php b/src/CompletionProvider.php
index 9a000e6..68c5a0c 100644
--- a/src/CompletionProvider.php
+++ b/src/CompletionProvider.php
@@ -415,7 +415,7 @@ class CompletionProvider
 
         // Walk the AST upwards until a scope boundary is met
         $level = $node;
-        while ($level && !ParserHelpers\isFunctionLike($level)) {
+        while ($level && !($level instanceof PhpParser\FunctionLike)) {
             // Walk siblings before the node
             $sibling = $level;
             while ($sibling = $sibling->getPreviousSibling()) {
@@ -429,7 +429,7 @@ class CompletionProvider
 
         // If the traversal ended because a function was met,
         // also add its parameters and closure uses to the result list
-        if ($level && ParserHelpers\isFunctionLike($level) && $level->parameters !== null) {
+        if ($level && $level instanceof PhpParser\FunctionLike && $level->parameters !== null) {
             foreach ($level->parameters->getValues() as $param) {
                 $paramName = $param->getName();
                 if (empty($namePrefix) || strpos($paramName, $namePrefix) !== false) {
diff --git a/src/DefinitionResolver.php b/src/DefinitionResolver.php
index 93f961d..620527e 100644
--- a/src/DefinitionResolver.php
+++ b/src/DefinitionResolver.php
@@ -509,7 +509,7 @@ class DefinitionResolver
         // Traverse the AST up
         do {
             // If a function is met, check the parameters and use statements
-            if (ParserHelpers\isFunctionLike($n)) {
+            if ($n instanceof PhpParser\FunctionLike) {
                 if ($n->parameters !== null) {
                     foreach ($n->parameters->getElements() as $param) {
                         if ($param->getName() === $name) {
@@ -1018,7 +1018,7 @@ class DefinitionResolver
         //   1. doc block
         //   2. return type hint
         //   3. TODO: infer from return statements
-        if (ParserHelpers\isFunctionLike($node)) {
+        if ($node instanceof PhpParser\FunctionLike) {
             // Functions/methods
             $docBlock = $this->getDocBlock($node);
             if (
diff --git a/src/ParserHelpers.php b/src/ParserHelpers.php
index 0ea210a..f20fb1f 100644
--- a/src/ParserHelpers.php
+++ b/src/ParserHelpers.php
@@ -25,7 +25,7 @@ function isConstantFetch(Node $node) : bool
             $parent instanceof Node\Expression\CallExpression ||
             $parent instanceof Node\Expression\ObjectCreationExpression ||
             $parent instanceof Node\Expression\ScopedPropertyAccessExpression ||
-            isFunctionLike($parent) ||
+            $parent instanceof PhpParser\FunctionLike ||
             (
                 $parent instanceof Node\Expression\BinaryExpression &&
                 $parent->operator->kind === PhpParser\TokenKind::InstanceOfKeyword
@@ -38,14 +38,6 @@ function getFunctionLikeDeclarationFromParameter(Node\Parameter $node)
     return $node->parent->parent;
 }
 
-function isFunctionLike(Node $node)
-{
-    return
-        $node instanceof Node\Statement\FunctionDeclaration ||
-        $node instanceof Node\MethodDeclaration ||
-        $node instanceof Node\Expression\AnonymousFunctionCreationExpression;
-}
-
 function isBooleanExpression($expression) : bool
 {
     if (!($expression instanceof Node\Expression\BinaryExpression)) {
diff --git a/src/TreeAnalyzer.php b/src/TreeAnalyzer.php
index 81c96e1..58de8db 100644
--- a/src/TreeAnalyzer.php
+++ b/src/TreeAnalyzer.php
@@ -72,10 +72,10 @@ class TreeAnalyzer
             $range = PhpParser\PositionUtilities::getRangeFromPosition($error->start, $error->length, $this->sourceFileNode->fileContents);
 
             switch ($error->kind) {
-                case \Microsoft\PhpParser\DiagnosticKind::Error:
+                case PhpParser\DiagnosticKind::Error:
                     $severity = DiagnosticSeverity::ERROR;
                     break;
-                case \Microsoft\PhpParser\DiagnosticKind::Warning:
+                case PhpParser\DiagnosticKind::Warning:
                 default:
                     $severity = DiagnosticSeverity::WARNING;
                     break;