diff --git a/src/Dependency/DependencyResolver.php b/src/Dependency/DependencyResolver.php
index 002b73f03c..80440237e4 100644
--- a/src/Dependency/DependencyResolver.php
+++ b/src/Dependency/DependencyResolver.php
@@ -7,10 +7,10 @@
 use PhpParser\Node\Expr\Closure;
 use PhpParser\Node\Name;
 use PhpParser\Node\Stmt\Foreach_;
-use PhpParser\Node\Stmt\Function_;
 use PHPStan\Analyser\Scope;
 use PHPStan\File\FileHelper;
 use PHPStan\Node\InClassMethodNode;
+use PHPStan\Node\InFunctionNode;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Reflection\ParametersAcceptorWithPhpDocs;
 use PHPStan\Reflection\ReflectionProvider;
@@ -61,15 +61,9 @@ public function resolveDependencies(\PhpParser\Node $node, Scope $scope): NodeDe
 					$this->extractFromParametersAcceptor($parametersAcceptor, $dependenciesReflections);
 				}
 			}
-		} elseif ($node instanceof Function_) {
-			$functionName = $node->name->name;
-			if (isset($node->namespacedName)) {
-				$functionName = (string) $node->namespacedName;
-			}
-			$functionNameName = new Name($functionName);
-			if ($this->reflectionProvider->hasFunction($functionNameName, null)) {
-				$functionReflection = $this->reflectionProvider->getFunction($functionNameName, null);
-
+		} elseif ($node instanceof InFunctionNode) {
+			$functionReflection = $scope->getFunction();
+			if ($functionReflection !== null) {
 				$parametersAcceptor = ParametersAcceptorSelector::selectSingle($functionReflection->getVariants());
 
 				if ($parametersAcceptor instanceof ParametersAcceptorWithPhpDocs) {
diff --git a/tests/PHPStan/Analyser/AnalyserIntegrationTest.php b/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
index afbda2777d..6ce6e7cdcc 100644
--- a/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
+++ b/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
@@ -279,6 +279,12 @@ public function testBug3798(): void
 		$this->assertCount(0, $errors);
 	}
 
+	public function testBug3909(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-3909.php');
+		$this->assertCount(0, $errors);
+	}
+
 	/**
 	 * @param string $file
 	 * @return \PHPStan\Analyser\Error[]
diff --git a/tests/PHPStan/Analyser/data/bug-3909.php b/tests/PHPStan/Analyser/data/bug-3909.php
new file mode 100644
index 0000000000..3dd72bcf2f
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-3909.php
@@ -0,0 +1,7 @@
+<?php
+
+if (!function_exists('pg_escape_string')) {
+	function pg_escape_string(): string {
+		return '';
+	}
+}