diff --git a/packages/PHPStanStaticTypeMapper/TypeMapper/UnionTypeMapper.php b/packages/PHPStanStaticTypeMapper/TypeMapper/UnionTypeMapper.php
index 5b4c94716e7..da5915b3fcc 100644
--- a/packages/PHPStanStaticTypeMapper/TypeMapper/UnionTypeMapper.php
+++ b/packages/PHPStanStaticTypeMapper/TypeMapper/UnionTypeMapper.php
@@ -126,7 +126,7 @@ public function mapToPhpParserNode(Type $type, string $typeKind): ?Node
         return $this->mapNullabledType($nullabledType, $typeKind);
     }
 
-    /** 
+    /**
      * @param TypeKind::* $typeKind
      */
     private function mapNullabledType(Type $nullabledType, string $typeKind): ?Node
diff --git a/rules-tests/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector/Fixture/case_insensitive_function_name.php.inc b/rules-tests/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector/Fixture/case_insensitive_function_name.php.inc
new file mode 100644
index 00000000000..a3cec9e97c7
--- /dev/null
+++ b/rules-tests/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector/Fixture/case_insensitive_function_name.php.inc
@@ -0,0 +1,27 @@
+<?php
+
+namespace Rector\Tests\Php80\Rector\FuncCall\NullToStrictStringFuncCallArgRector\Fixture;
+
+final class CaseInsensitiveFunctionName
+{
+    public function run($var)
+    {
+        return strToLower($var);
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\Php80\Rector\FuncCall\NullToStrictStringFuncCallArgRector\Fixture;
+
+final class CaseInsensitiveFunctionName
+{
+    public function run($var)
+    {
+        return strToLower((string) $var);
+    }
+}
+
+?>
diff --git a/rules/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector.php b/rules/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector.php
index d9131cdcc5a..6b79fa09644 100644
--- a/rules/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector.php
+++ b/rules/Php81/Rector/FuncCall/NullToStrictStringFuncCallArgRector.php
@@ -484,7 +484,7 @@ private function resolveOriginalPositions(FuncCall $funcCall): array
             $funcCall,
             $scope
         );
-        $functionName = $this->nodeNameResolver->getName($funcCall);
+        $functionName = $functionReflection->getName();
         $argNames = self::ARG_POSITION_NAME_NULL_TO_STRICT_STRING[$functionName];
         $positions = [];
 
diff --git a/rules/TypeDeclaration/TypeAnalyzer/AlwaysStrictScalarExprAnalyzer.php b/rules/TypeDeclaration/TypeAnalyzer/AlwaysStrictScalarExprAnalyzer.php
index 466b652a19f..83ded2e3588 100644
--- a/rules/TypeDeclaration/TypeAnalyzer/AlwaysStrictScalarExprAnalyzer.php
+++ b/rules/TypeDeclaration/TypeAnalyzer/AlwaysStrictScalarExprAnalyzer.php
@@ -56,7 +56,7 @@ public function matchStrictScalarExpr(Expr $expr): ?Type
         if ($expr instanceof FuncCall) {
             $returnType = $this->resolveFuncCallType($expr);
 
-            if ($returnType === null) {
+            if (! $returnType instanceof Type) {
                 return null;
             }
 
@@ -84,11 +84,7 @@ private function isScalarType(Type $type): bool
             return true;
         }
 
-        if ($type instanceof BooleanType) {
-            return true;
-        }
-
-        return false;
+        return $type instanceof BooleanType;
     }
 
     private function resolveTypeFromScalar(Scalar $scalar): Type|null