diff --git a/README.md b/README.md
index 5998c6a..079b0f8 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ For this reason, we have written this plugin, which — in addition to addressin
   - [php_namespace](#php_namespace) 
   - [src_path](#src_path)
   - [grpc](#grpc)
+  - [memory limit](#memory-limit)
   - [multiple options](#multiple-options)
 - [Generated code guide](#generated-code-guide)
     - [numbers](#numbers)
@@ -170,6 +171,32 @@ protoc \
 
 To generate only the server code, use `grpc=server`. By default, and when passing `grpc=client,grpc=server`, both the client and server will be generated.
 
+### `memory limit`
+
+When processing very large schemas, the default PHP `memory_limit` (often `128M`) may be insufficient and lead to plugin exit code `255`.
+
+The plugin now ensures at least `512M` by default. If you need a different value, override it with the `THESIS_PLUGIN_MEMORY_LIMIT` environment variable.
+
+When using a locally installed plugin:
+```shell
+THESIS_PLUGIN_MEMORY_LIMIT=1G protoc \
+  --plugin=protoc-gen-php-plugin=/usr/local/bin/protoc-gen-php \
+  protos/*.proto \
+  --php-plugin_out=genproto
+```
+
+When using the Docker image:
+```shell
+docker run --rm \
+  --user $(id -u):$(id -g) \
+  -e THESIS_PLUGIN_MEMORY_LIMIT=1G \
+  -v "$(PWD):/workspace" \
+  -w /workspace \
+  ghcr.io/thesis-php/protoc-plugin:latest \
+  --php-plugin_out=genproto \
+  protos/*.proto
+```
+
 ### Multiple options
 
 You can pass multiple options separated by commas. For example, if you want to specify a different namespace, place all the code in the root directory, and generate only the `gRPC` client, you can write the following:
diff --git a/bin/compiler.php b/bin/compiler.php
index 325669e..febf52a 100755
--- a/bin/compiler.php
+++ b/bin/compiler.php
@@ -5,6 +5,17 @@
 
 require_once __DIR__ . '/../vendor/autoload.php';
 
+if (is_string($configuredMemoryLimit = getenv('THESIS_PLUGIN_MEMORY_LIMIT'))) {
+    @ini_set('memory_limit', $configuredMemoryLimit);
+} else {
+    $memoryLimitBytes = ini_parse_quantity(ini_get('memory_limit'));
+
+    // We should increase memory_limit if it is lower than 512M.
+    if ($memoryLimitBytes !== -1 && $memoryLimitBytes < 512 * 1_024 * 1_024) {
+        @ini_set('memory_limit', '512M');
+    }
+}
+
 use Thesis\Protobuf\Decoder;
 use Thesis\Protobuf\Encoder;
 use Thesis\Protoc;
diff --git a/tests/CompilerMemoryLimitTest.php b/tests/CompilerMemoryLimitTest.php
new file mode 100644
index 0000000..4f280e7
--- /dev/null
+++ b/tests/CompilerMemoryLimitTest.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Thesis\Protoc;
+
+use PHPUnit\Framework\Attributes\CoversNothing;
+use PHPUnit\Framework\TestCase;
+
+#[CoversNothing]
+final class CompilerMemoryLimitTest extends TestCase
+{
+    public function testCompilerUsesMemoryLimitFromEnvironment(): void
+    {
+        $memoryLimit = self::runCompilerScript(
+            initialMemoryLimit: '64M',
+            envMemoryLimit: '1G',
+        );
+
+        self::assertSame('1G', $memoryLimit);
+    }
+
+    public function testCompilerRaisesDefaultMemoryLimitTo512M(): void
+    {
+        $memoryLimit = self::runCompilerScript(
+            initialMemoryLimit: '64M',
+        );
+
+        self::assertSame('512M', $memoryLimit);
+    }
+
+    private static function runCompilerScript(string $initialMemoryLimit, ?string $envMemoryLimit = null): string
+    {
+        $code = <<<'PHP'
+require 'bin/compiler.php';
+fwrite(STDERR, "\nMEMORY_LIMIT=" . ini_get('memory_limit') . "\n");
+PHP;
+
+        $process = proc_open(
+            [PHP_BINARY, '-d', "memory_limit={$initialMemoryLimit}", '-r', $code],
+            [
+                0 => ['file', '/dev/null', 'r'],
+                1 => ['file', '/dev/null', 'w'],
+                2 => ['pipe', 'w'],
+            ],
+            $pipes,
+            \dirname(__DIR__),
+            $envMemoryLimit !== null
+                ? ['THESIS_PLUGIN_MEMORY_LIMIT' => $envMemoryLimit]
+                : [],
+        );
+
+        self::assertIsResource($process);
+        self::assertArrayHasKey(2, $pipes);
+
+        $stderr = stream_get_contents($pipes[2]);
+        fclose($pipes[2]);
+        self::assertIsString($stderr);
+
+        self::assertSame(0, proc_close($process), $stderr);
+
+        self::assertMatchesRegularExpression('/MEMORY_LIMIT=(.+)\n/', $stderr);
+        preg_match('/MEMORY_LIMIT=(.+)\n/', $stderr, $matches);
+
+        return trim($matches[1] ?? '');
+    }
+}