diff --git a/src/Analyser/NodeScopeResolver.php b/src/Analyser/NodeScopeResolver.php
index b85f2cbd94..02db119f5c 100644
--- a/src/Analyser/NodeScopeResolver.php
+++ b/src/Analyser/NodeScopeResolver.php
@@ -1188,7 +1188,7 @@ private function processStmtNode(
 					$scopeForBranches = $caseResult->getScope();
 					$hasYield = $hasYield || $caseResult->hasYield();
 					$throwPoints = array_merge($throwPoints, $caseResult->getThrowPoints());
-					$branchScope = $scopeForBranches->filterByTruthyValue($condExpr);
+					$branchScope = $caseResult->getTruthyScope()->filterByTruthyValue($condExpr);
 				} else {
 					$hasDefaultCase = true;
 					$branchScope = $scopeForBranches;
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index d444010cd5..06cc71c72c 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -3983,7 +3983,7 @@ public function testNotSwitchInstanceof(): void
 	{
 		$this->assertTypes(
 			__DIR__ . '/data/switch-instanceof-not.php',
-			'*ERROR*',
+			'*NEVER*',
 			'$foo',
 		);
 	}
diff --git a/tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php b/tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php
index f78377e721..9d84ab9035 100644
--- a/tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php
+++ b/tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php
@@ -967,4 +967,13 @@ public function testBug9474(): void
 		$this->analyse([__DIR__ . '/data/bug-9474.php'], []);
 	}
 
+	public function testBug5326(): void
+	{
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = true;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+		$this->analyse([__DIR__ . '/data/bug-5326.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Variables/data/bug-5326.php b/tests/PHPStan/Rules/Variables/data/bug-5326.php
new file mode 100644
index 0000000000..f1c87aecae
--- /dev/null
+++ b/tests/PHPStan/Rules/Variables/data/bug-5326.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Bug5326;
+
+function normalize(string $value): string
+{
+	switch (true) {
+		case strpos($value, 'get_') === 0 && preg_match('/get_(\S+)/m', $value, $match) === 1:
+			return $match[1];
+		default:
+			return $value;
+	}
+}