diff --git a/src/Flex.php b/src/Flex.php
index 6c53270a..5461c3eb 100644
--- a/src/Flex.php
+++ b/src/Flex.php
@@ -39,6 +39,7 @@
 use Composer\Plugin\PrePoolCreateEvent;
 use Composer\Script\Event;
 use Composer\Script\ScriptEvents;
+use Composer\Semver\Constraint\Constraint;
 use Composer\Semver\VersionParser;
 use Symfony\Component\Console\Exception\ExceptionInterface as ConsoleExceptionInterface;
 use Symfony\Component\Console\Input\ArgvInput;
@@ -219,7 +220,15 @@ class_exists(__NAMESPACE__.str_replace('/', '\\', substr($file, \strlen(__DIR__)
             break;
         }
 
-        $symfonyRequire = preg_replace('/\.x$/', '.x-dev', getenv('SYMFONY_REQUIRE') ?: ($composer->getPackage()->getExtra()['symfony']['require'] ?? ''));
+        $rawSymfonyRequire = getenv('SYMFONY_REQUIRE') ?: ($composer->getPackage()->getExtra()['symfony']['require'] ?? '');
+        $symfonyRequire = preg_replace('/\.x$/', '.x-dev', $rawSymfonyRequire);
+
+        if ($rawSymfonyRequire) {
+            $parsedConstraint = (new VersionParser())->parseConstraints($rawSymfonyRequire);
+            if ($parsedConstraint instanceof Constraint && '==' === $parsedConstraint->getOperator()) {
+                $io->writeError(\sprintf('<warning>SYMFONY_REQUIRE="%s" is an exact version constraint. Did you mean "%s.*" or "^%s"?</>', $rawSymfonyRequire, $rawSymfonyRequire, $rawSymfonyRequire));
+            }
+        }
 
         if ($symfonyRequire || $this->ignorePreleases) {
             $this->filter = new PackageFilter($io, $symfonyRequire, $this->downloader, $this->ignorePreleases);
diff --git a/tests/FlexTest.php b/tests/FlexTest.php
index ef82da5b..f4c51741 100644
--- a/tests/FlexTest.php
+++ b/tests/FlexTest.php
@@ -111,6 +111,47 @@ public function testPostInstall()
         );
     }
 
+    #[DataProvider('getSymfonyRequireConstraints')]
+    public function testSymfonyRequireExactVersionWarning(string $constraint, bool $expectWarning)
+    {
+        $io = new BufferIO('', OutputInterface::VERBOSITY_VERBOSE);
+
+        $package = $this->mockRootPackage();
+        $package->method('getRequires')->willReturn([new Link('dummy', 'symfony/flex', class_exists(MatchAllConstraint::class) ? new MatchAllConstraint() : null)]);
+
+        $composer = $this->mockComposer($this->mockLocker(), $package, Factory::createConfig($io));
+        if (version_compare('2.0.0', PluginInterface::PLUGIN_API_VERSION, '>')) {
+            $composer->setRepositoryManager($this->mockManager());
+        }
+
+        putenv('SYMFONY_REQUIRE='.$constraint);
+        try {
+            (new Flex())->activate($composer, $io);
+        } finally {
+            putenv('SYMFONY_REQUIRE');
+        }
+
+        if ($expectWarning) {
+            $this->assertStringContainsString(\sprintf('SYMFONY_REQUIRE="%s" is an exact version constraint', $constraint), $io->getOutput());
+        } else {
+            $this->assertStringNotContainsString('is an exact version constraint', $io->getOutput());
+        }
+    }
+
+    public static function getSymfonyRequireConstraints(): array
+    {
+        return [
+            'exact major' => ['7', true],
+            'exact minor' => ['7.4', true],
+            'exact patch' => ['7.4.1', true],
+            'caret' => ['^7.4', false],
+            'tilde' => ['~7.4', false],
+            'wildcard' => ['7.4.*', false],
+            'greater or equal' => ['>=7.4', false],
+            'x-range' => ['7.4.x', false],
+        ];
+    }
+
     public function testActivateLoadsClasses()
     {
         $io = new BufferIO('', OutputInterface::VERBOSITY_VERBOSE);