diff --git a/src/Analyser/FileAnalysisProvider.php b/src/Analyser/FileAnalysisProvider.php
index 2e18bbb..53c2277 100644
--- a/src/Analyser/FileAnalysisProvider.php
+++ b/src/Analyser/FileAnalysisProvider.php
@@ -8,11 +8,14 @@
 use Boundwize\StructArmed\Util\Path;
 use PhpParser\Error;
 use PhpParser\Node;
+use PhpParser\Node\Expr\FuncCall;
+use PhpParser\Node\Name;
 use PhpParser\Node\Stmt;
 use PhpParser\Node\Stmt\ClassLike;
 use PhpParser\Node\Stmt\Const_;
 use PhpParser\Node\Stmt\Declare_;
 use PhpParser\Node\Stmt\Else_;
+use PhpParser\Node\Stmt\Expression;
 use PhpParser\Node\Stmt\Function_;
 use PhpParser\Node\Stmt\GroupUse;
 use PhpParser\Node\Stmt\If_;
@@ -285,7 +288,21 @@ private function isSymbolDeclaration(Stmt $stmt): bool
     {
         return $stmt instanceof ClassLike
             || $stmt instanceof Function_
-            || $stmt instanceof Const_;
+            || $stmt instanceof Const_
+            || $this->isDefineCall($stmt);
+    }
+
+    /**
+     * A top-level `define('CONST', ...)` call declares a constant symbol under PSR-1,
+     * mirroring PHP_CodeSniffer's PSR1.Files.SideEffects sniff. Method calls such as
+     * `$obj->define(...)` or `Foo::define(...)` are not FuncCall nodes, so they never match.
+     */
+    private function isDefineCall(Stmt $stmt): bool
+    {
+        return $stmt instanceof Expression
+            && $stmt->expr instanceof FuncCall
+            && $stmt->expr->name instanceof Name
+            && $stmt->expr->name->toLowerString() === 'define';
     }
 
     private function isNeutralStatement(Stmt $stmt): bool
diff --git a/tests/Rule/File/Psr1SymbolsOrSideEffectsRuleTest.php b/tests/Rule/File/Psr1SymbolsOrSideEffectsRuleTest.php
index dd3048b..ac907b9 100644
--- a/tests/Rule/File/Psr1SymbolsOrSideEffectsRuleTest.php
+++ b/tests/Rule/File/Psr1SymbolsOrSideEffectsRuleTest.php
@@ -174,6 +174,104 @@ final class Foo {}
         }
     }
 
+    public function testPassesDefineConstantNextToClass(): void
+    {
+        $basePath = $this->makeTempDir();
+
+        try {
+            mkdir($basePath . '/src');
+            file_put_contents(
+                $basePath . '/src/Foo.php',
+                "<?php\ndefine('APP_VERSION', '1.2.3');\nclass Bootstrap {}\n"
+            );
+
+            $violations = (new Psr1SymbolsOrSideEffectsRule(['src/']))->evaluateProjectAll(
+                $basePath,
+                Architecture::define()
+            );
+
+            $this->assertSame([], $violations);
+        } finally {
+            unlink($basePath . '/src/Foo.php');
+            rmdir($basePath . '/src');
+            rmdir($basePath);
+        }
+    }
+
+    public function testPassesDefinedGuardedDefineNextToClass(): void
+    {
+        $basePath = $this->makeTempDir();
+
+        try {
+            mkdir($basePath . '/src');
+            file_put_contents(
+                $basePath . '/src/Foo.php',
+                "<?php\nif (! defined('APP_VERSION')) {\n    define('APP_VERSION', '1.2.3');\n}\nclass Bootstrap {}\n"
+            );
+
+            $violations = (new Psr1SymbolsOrSideEffectsRule(['src/']))->evaluateProjectAll(
+                $basePath,
+                Architecture::define()
+            );
+
+            $this->assertSame([], $violations);
+        } finally {
+            unlink($basePath . '/src/Foo.php');
+            rmdir($basePath . '/src');
+            rmdir($basePath);
+        }
+    }
+
+    public function testViolatesEchoNextToDefineAndClass(): void
+    {
+        $basePath = $this->makeTempDir();
+
+        try {
+            mkdir($basePath . '/src');
+            file_put_contents(
+                $basePath . '/src/Foo.php',
+                "<?php\ndefine('APP_VERSION', '1.2.3');\necho 'x';\nclass Bootstrap {}\n"
+            );
+
+            $violations = (new Psr1SymbolsOrSideEffectsRule(['src/']))->evaluateProjectAll(
+                $basePath,
+                Architecture::define()
+            );
+
+            $this->assertCount(1, $violations);
+            $this->assertSame(3, $violations[0]->line);
+        } finally {
+            unlink($basePath . '/src/Foo.php');
+            rmdir($basePath . '/src');
+            rmdir($basePath);
+        }
+    }
+
+    public function testViolatesDefineMixedWithSideEffectCall(): void
+    {
+        $basePath = $this->makeTempDir();
+
+        try {
+            mkdir($basePath . '/src');
+            file_put_contents(
+                $basePath . '/src/Foo.php',
+                "<?php\ndefine('APP_VERSION', '1.2.3');\nsession_start();\n"
+            );
+
+            $violations = (new Psr1SymbolsOrSideEffectsRule(['src/']))->evaluateProjectAll(
+                $basePath,
+                Architecture::define()
+            );
+
+            $this->assertCount(1, $violations);
+            $this->assertSame(3, $violations[0]->line);
+        } finally {
+            unlink($basePath . '/src/Foo.php');
+            rmdir($basePath . '/src');
+            rmdir($basePath);
+        }
+    }
+
     public function testViolatesConditionalSideEffectNextToSymbol(): void
     {
         $basePath = $this->makeTempDir();