diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/NonDivArithmeticOpAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/NonDivArithmeticOpAnalyzer.php
index e293eb13d..7e59c0527 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/NonDivArithmeticOpAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/NonDivArithmeticOpAnalyzer.php
@@ -288,6 +288,48 @@ class NonDivArithmeticOpAnalyzer
         bool &$has_string_increment,
         Type\Union &$result_type = null
     ): ?Type\Union {
+        if ($left_type_part instanceof TLiteralInt
+            && $right_type_part instanceof TLiteralInt
+            && ($left instanceof PhpParser\Node\Scalar || $left instanceof PhpParser\Node\Expr\ConstFetch)
+            && ($right instanceof PhpParser\Node\Scalar || $right instanceof PhpParser\Node\Expr\ConstFetch)
+        ) {
+            // time for some arithmetic!
+
+            $calculated_type = null;
+
+            if ($parent instanceof PhpParser\Node\Expr\BinaryOp\Plus) {
+                $calculated_type = Type::getInt(false, $left_type_part->value + $right_type_part->value);
+            } elseif ($parent instanceof PhpParser\Node\Expr\BinaryOp\Minus) {
+                $calculated_type = Type::getInt(false, $left_type_part->value - $right_type_part->value);
+            } elseif ($parent instanceof PhpParser\Node\Expr\BinaryOp\Mod) {
+                $calculated_type = Type::getInt(false, $left_type_part->value % $right_type_part->value);
+            } elseif ($parent instanceof PhpParser\Node\Expr\BinaryOp\Mul) {
+                $calculated_type = Type::getInt(false, $left_type_part->value * $right_type_part->value);
+            } elseif ($parent instanceof PhpParser\Node\Expr\BinaryOp\Pow) {
+                $calculated_type = Type::getInt(false, $left_type_part->value ^ $right_type_part->value);
+            } elseif ($parent instanceof PhpParser\Node\Expr\BinaryOp\BitwiseOr) {
+                $calculated_type = Type::getInt(false, $left_type_part->value | $right_type_part->value);
+            } elseif ($parent instanceof PhpParser\Node\Expr\BinaryOp\BitwiseAnd) {
+                $calculated_type = Type::getInt(false, $left_type_part->value & $right_type_part->value);
+            }
+
+            if ($calculated_type) {
+                if ($result_type) {
+                    $result_type = Type::combineUnionTypes(
+                        $calculated_type,
+                        $result_type
+                    );
+                } else {
+                    $result_type = $calculated_type;
+                }
+
+                $has_valid_left_operand = true;
+                $has_valid_right_operand = true;
+
+                return null;
+            }
+        }
+
         if ($left_type_part instanceof TNull || $right_type_part instanceof TNull) {
             // null case is handled above
             return null;
diff --git a/stubs/CoreGenericFunctions.phpstub b/stubs/CoreGenericFunctions.phpstub
index adec2461b..b4bcaaff9 100644
--- a/stubs/CoreGenericFunctions.phpstub
+++ b/stubs/CoreGenericFunctions.phpstub
@@ -607,7 +607,11 @@ function explode(string $delimiter, string $string, int $limit = -1) : array {}
  *
  * @psalm-flow ($subject) -(array-assignment)-> return
  *
- * @return ($flags is 0 ? non-empty-list<string>|false : list<string>|list<list<string|int>>|false)
+ * @template TFlags as 0|1|2|3|4|5|6|7
+ *
+ * @param TFlags $flags
+ *
+ * @return (TFlags is 0|2 ? non-empty-list<string>|false : (TFlags is 1|3 ? list<string>|false : list<array{string,int}>|false))
  *
  * @psalm-ignore-falsable-return
  */
diff --git a/tests/BinaryOperationTest.php b/tests/BinaryOperationTest.php
index 124daa62d..d83ba51e4 100644
--- a/tests/BinaryOperationTest.php
+++ b/tests/BinaryOperationTest.php
@@ -133,7 +133,7 @@ class BinaryOperationTest extends TestCase
                     $c = 25 % 2.5;
                     $d = 25.5 % 2.5;',
                 'assertions' => [
-                    '$a' => 'int|int',
+                    '$a' => 'int',
                     '$b' => 'int',
                     '$c' => 'int',
                     '$d' => 'int',
diff --git a/tests/FunctionCallTest.php b/tests/FunctionCallTest.php
index e3f6c2fbb..bd36030f2 100644
--- a/tests/FunctionCallTest.php
+++ b/tests/FunctionCallTest.php
@@ -1362,6 +1362,13 @@ class FunctionCallTest extends TestCase
                         return preg_split("/ /", $s);
                     }'
             ],
+            'pregSplitWithFlags' => [
+                '<?php
+                    /** @return list<string> */
+                    function foo(string $s) {
+                        return preg_split("/ /", $s, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
+                    }'
+            ],
             'mbConvertEncodingWithArray' => [
                 '<?php
                     /**
diff --git a/tests/TypeReconciliation/TypeTest.php b/tests/TypeReconciliation/TypeTest.php
index 529dbbcae..d765713f0 100644
--- a/tests/TypeReconciliation/TypeTest.php
+++ b/tests/TypeReconciliation/TypeTest.php
@@ -242,7 +242,7 @@ class TypeTest extends \Psalm\Tests\TestCase
                     class B {
                         /** @return void */
                         public function barBar(One $one = null, Two $two = null) {
-                            if ($one !== null && ($two || 1 + 1 === 3)) {
+                            if ($one !== null && ($two || rand(0, 1))) {
                                 $one->fooFoo();
                             }
                         }