diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index 543d6e30b3..880b195123 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -2503,7 +2503,11 @@ public function unsetExpression(Expr $expr): self
 				);
 			}
 
-			return $this->invalidateExpression($expr->var)->invalidateExpression(new FuncCall(new Name('count'), [new Node\Arg($expr->var)]));
+			$args = [new Node\Arg($expr->var)];
+
+			return $this->invalidateExpression($expr->var)
+				->invalidateExpression(new FuncCall(new Name\FullyQualified('count'), $args))
+				->invalidateExpression(new FuncCall(new Name('count'), $args));
 		}
 
 		return $this;
diff --git a/tests/PHPStan/Analyser/data/bug-2648.php b/tests/PHPStan/Analyser/data/bug-2648.php
index 9bc3e2f523..1013149503 100644
--- a/tests/PHPStan/Analyser/data/bug-2648.php
+++ b/tests/PHPStan/Analyser/data/bug-2648.php
@@ -34,6 +34,8 @@ public function doBar(array $list): void
 					assertType('int', count($list));
 				}
 
+				assertType('int', count($list));
+
 				if (count($list) === 1) {
 					assertType('int', count($list));
 					break;
diff --git a/tests/PHPStan/Rules/Comparison/NumberComparisonOperatorsConstantConditionRuleTest.php b/tests/PHPStan/Rules/Comparison/NumberComparisonOperatorsConstantConditionRuleTest.php
index 1732c56769..aa828378d7 100644
--- a/tests/PHPStan/Rules/Comparison/NumberComparisonOperatorsConstantConditionRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/NumberComparisonOperatorsConstantConditionRuleTest.php
@@ -34,4 +34,14 @@ public function testRule(): void
 		]);
 	}
 
+	public function testBug2648(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-2648-rule.php'], []);
+	}
+
+	public function testBug2648Namespace(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-2648-namespace-rule.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-2648-namespace-rule.php b/tests/PHPStan/Rules/Comparison/data/bug-2648-namespace-rule.php
new file mode 100644
index 0000000000..c969d7e9c2
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-2648-namespace-rule.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Bug2648Rule;
+
+/** @var array<string> $foo */
+$foo = $_GET['bar'];
+
+if (count($foo) > 0) {
+	foreach ($foo as $key => $value) {
+		unset($foo[$key]);
+	}
+
+	if(count($foo) > 0) {
+		// $foo is actually empty now
+	}
+}
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-2648-rule.php b/tests/PHPStan/Rules/Comparison/data/bug-2648-rule.php
new file mode 100644
index 0000000000..ebd83be1be
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-2648-rule.php
@@ -0,0 +1,14 @@
+<?php
+
+/** @var array<string> $foo */
+$foo = $_GET['bar'];
+
+if (count($foo) > 0) {
+	foreach ($foo as $key => $value) {
+		unset($foo[$key]);
+	}
+
+	if(count($foo) > 0) {
+		// $foo is actually empty now
+	}
+}