diff --git a/src/Parser/TypeConversionTrait.php b/src/Parser/TypeConversionTrait.php
index 6312298d..b1a7c020 100644
--- a/src/Parser/TypeConversionTrait.php
+++ b/src/Parser/TypeConversionTrait.php
@@ -56,7 +56,8 @@ protected function convertIntExpr(string $expr, string $fromType = ''): string
             default => null,
         };
         if ($bigConversion !== null) {
-            return $bigConversion . '(' . $expr . ')';
+            // The Big* conversions return a php::Variant; unwrap it to the native scalar.
+            return 'php::toInt(' . $bigConversion . '(' . $expr . '))';
         }
         if (!$this->isClosedExpr($expr, 'php::toInt')) {
             return 'php::toInt(' . $expr . ')';
@@ -74,7 +75,8 @@ protected function convertFloatExpr(string $expr, string $fromType = ''): string
             default => null,
         };
         if ($bigConversion !== null) {
-            return $bigConversion . '(' . $expr . ')';
+            // The Big* conversions return a php::Variant; unwrap it to the native scalar.
+            return 'php::toFloat(' . $bigConversion . '(' . $expr . '))';
         }
         if (!$this->isClosedExpr($expr, 'php::toFloat')) {
             return 'php::toFloat(' . $expr . ')';
@@ -184,7 +186,8 @@ protected function convertBoolExpr(string $expr, string $fromType = ''): string
             default => null,
         };
         if ($bigConversion !== null) {
-            return $bigConversion . '(' . $expr . ')';
+            // The Big* conversions return a php::Variant; unwrap it to the native scalar.
+            return 'php::toBool(' . $bigConversion . '(' . $expr . '))';
         }
         if (!$this->isClosedExpr($expr, 'php::toBool')) {
             return 'php::toBool(' . $expr . ')';
@@ -203,16 +206,25 @@ protected function convertConditionExpr(NodeAbstract $node, string $expr): strin
         return $this->convertBoolExpr($expr, $type);
     }
 
+    protected function bigNumberTypeOf(mixed $type): ?string
+    {
+        return in_array($type, [Type::BIGINT, Type::BIGFLOAT, Type::DECIMAL], true) ? $type : null;
+    }
+
     protected function convertExprType(string $expr, $leftType, $rightType): string
     {
+        // A BigInt/BigFloat/Decimal operand is a php::Box resource. The generic
+        // php::toFloat()/php::toInt() would read its resource handle, so the
+        // conversion must go through the high-precision type itself.
+        $bigType = $this->bigNumberTypeOf($rightType) ?? $this->bigNumberTypeOf($leftType) ?? '';
         if ($leftType === Type::FLOAT or $rightType === Type::FLOAT) {
-            return $this->convertFloatExpr($expr);
+            return $this->convertFloatExpr($expr, $bigType);
         }
         if ($leftType === Type::INT or $rightType === Type::INT) {
-            return $this->convertIntExpr($expr);
+            return $this->convertIntExpr($expr, $bigType);
         }
         if ($leftType === Type::BOOL or $rightType === Type::BOOL) {
-            return $this->convertBoolExpr($expr);
+            return $this->convertBoolExpr($expr, $bigType);
         }
 
         return $expr;
diff --git a/tests/compiler/bignumber/native-scalar-conversions.phpt b/tests/compiler/bignumber/native-scalar-conversions.phpt
new file mode 100755
index 00000000..59afa2c2
--- /dev/null
+++ b/tests/compiler/bignumber/native-scalar-conversions.phpt
@@ -0,0 +1,46 @@
+--TEST--
+BigInt/BigFloat/Decimal values convert by value (not by box resource handle) into native int/float/bool slots
+--FILE--
+<?php
+function takesFloat(float $x): float { return $x; }
+function takesInt(int $x): int { return $x; }
+function takesBool(bool $x): bool { return $x; }
+
+// A float literal with 16+ fractional digits is recognized as a Decimal literal.
+function returnsFloatFromDecimalLiteral(): float { return 0.123456789012345678; }
+function returnsIntFromBigInt(): int { return std::bigInt('42'); }
+
+function main(): void
+{
+    // Arguments
+    var_dump(takesFloat(0.123456789012345678));
+    var_dump(takesFloat(std::decimal('1.5')));
+    var_dump(takesFloat(std::bigInt('42')));
+    var_dump(takesFloat(std::bigFloat('2.25')));
+    var_dump(takesInt(std::bigInt('42')));
+    var_dump(takesInt(std::decimal('7.9')));
+    var_dump(takesBool(std::bigInt('0')));
+    var_dump(takesBool(std::decimal('0.5')));
+
+    // Returns
+    var_dump(returnsFloatFromDecimalLiteral());
+    var_dump(returnsIntFromBigInt());
+
+    // A fixed native local receiving a Decimal literal
+    $f = 0.0;
+    $f = 0.123456789012345678;
+    var_dump($f);
+}
+?>
+--EXPECT--
+float(0.12345678901234568)
+float(1.5)
+float(42)
+float(2.25)
+int(42)
+int(7)
+bool(false)
+bool(true)
+float(0.12345678901234568)
+int(42)
+float(0.12345678901234568)