diff --git a/phpunit/code/float-constant-precision.php b/phpunit/code/float-constant-precision.php
new file mode 100644
index 00000000..d5b8abf6
--- /dev/null
+++ b/phpunit/code/float-constant-precision.php
@@ -0,0 +1,13 @@
+<?php
+/**
+ * This file is part of TypePHP(AOT).
+ *
+ * @link     https://www.swoole.com/aot/
+ * @contact  service@swoole.com
+ */
+
+function main(): void
+{
+    var_dump(M_E);
+    var_dump(log(M_E));
+}
diff --git a/phpunit/src/CompilerBaseApiTest.php b/phpunit/src/CompilerBaseApiTest.php
index 9ae09b1b..183dc015 100644
--- a/phpunit/src/CompilerBaseApiTest.php
+++ b/phpunit/src/CompilerBaseApiTest.php
@@ -361,7 +361,9 @@ public function testWindowsIntegerLiteralSuffixForGeneratedCValues(): void
 
     public function testGeneratedCValuesAreAlwaysSourceCodeStrings(): void
     {
-        $this->assertSame((string) M_E, $this->invokeMethod('genCValue', M_E));
+        // A string cast here would follow the precision ini, so the assertion
+        // is that the emitted literal reads back as the same double.
+        $this->assertSame(M_E, (float) $this->invokeMethod('genCValue', M_E));
         $this->assertSame('1', $this->invokeMethod('genCValue', true));
         $this->assertSame('0', $this->invokeMethod('genCValue', false));
 
@@ -370,7 +372,7 @@ public function testGeneratedCValuesAreAlwaysSourceCodeStrings(): void
             new \PhpParser\Node\Expr\ConstFetch(new \PhpParser\Node\Name('M_E'))
         );
         $this->assertIsString($code);
-        $this->assertSame((string) M_E, $code);
+        $this->assertSame(M_E, (float) $code);
     }
 
     public function testNumericStringIdentifiersGenerateSourceCodeStrings(): void
diff --git a/phpunit/src/FloatLiteralPrecisionTest.php b/phpunit/src/FloatLiteralPrecisionTest.php
new file mode 100644
index 00000000..df961a32
--- /dev/null
+++ b/phpunit/src/FloatLiteralPrecisionTest.php
@@ -0,0 +1,50 @@
+<?php
+/**
+ * This file is part of TypePHP(AOT).
+ *
+ * @link     https://www.swoole.com/aot/
+ * @contact  service@swoole.com
+ */
+
+namespace TypePhp\Tests;
+
+use PHPUnit\Framework\TestCase;
+use TypePhp\CompilerTest;
+
+/**
+ * @internal
+ * @coversNothing
+ */
+class FloatLiteralPrecisionTest extends TestCase
+{
+    public function testFloatConstantsIgnoreThePrecisionIniOfTheHost(): void
+    {
+        // precision=14 is the PHP default, so this is what most hosts compile
+        // with. The constant baked into the binary must not depend on it.
+        $previous = ini_set('precision', '14');
+
+        try {
+            $cpp = $this->compileToCpp('float-constant-precision.php');
+        } finally {
+            if ($previous !== false) {
+                ini_set('precision', $previous);
+            }
+        }
+
+        self::assertStringContainsString('2.7182818284590451', $cpp);
+        self::assertStringNotContainsString('2.718281828459)', $cpp);
+    }
+
+    private function compileToCpp(string $file): string
+    {
+        global $translator;
+
+        $compiler = CompilerTest::create(TYPEPHP_ROOT_PATH);
+        $translator = $compiler;
+        $source = TYPEPHP_ROOT_PATH . '/phpunit/code/' . $file;
+        $compiler->addFiles([$source]);
+        $compiler->prepareFile($source);
+
+        return file_get_contents($compiler->convertFile($source));
+    }
+}
diff --git a/phpunit/src/Generator/UtilsTest.php b/phpunit/src/Generator/UtilsTest.php
index cc2264ea..56870e62 100644
--- a/phpunit/src/Generator/UtilsTest.php
+++ b/phpunit/src/Generator/UtilsTest.php
@@ -49,7 +49,12 @@ public function testGenCValueInt(): void
     public function testGenCValueFloat(): void
     {
         $result = $this->invokeMethod('genCValue', 3.14);
-        $this->assertSame((string) 3.14, $result);
+
+        // The literal has to read back as the same double. Its exact spelling
+        // is not part of the contract, but a string cast would depend on the
+        // precision ini and lose digits.
+        $this->assertSame(3.14, (float) $result);
+        $this->assertMatchesRegularExpression('/[.E]/i', $result);
     }
 
     public function testGenCValueBool(): void
diff --git a/src/Generator/Utils.php b/src/Generator/Utils.php
index c243d81a..937c9809 100644
--- a/src/Generator/Utils.php
+++ b/src/Generator/Utils.php
@@ -31,7 +31,9 @@ protected function genCValue(mixed $value): string
             return $this->genIntegerLiteral($value);
         }
         if (is_float($value)) {
-            return (string) $value;
+            // A string cast formats with the precision ini, which defaults to
+            // 14 and would bake a truncated constant into the binary.
+            return $this->genFloatLiteral($value);
         }
         if (is_bool($value)) {
             return $value ? '1' : '0';