diff --git a/.travis.yml b/.travis.yml
index fed7afe..d6647d3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -56,8 +56,10 @@ matrix:
                 export -f install_test
 
           script:
-              # Test that we find Guzzle
-              - install_test will-find "Http\Discovery\HttpClientDiscovery::find();" "php-http/guzzle6-adapter"
+              # Test that we find Guzzle 6 v1
+              - install_test will-find "Http\Discovery\HttpClientDiscovery::find();" "php-http/guzzle6-adapter:^1.1.1"
+              # Test that we find Guzzle 6 v2
+              - install_test will-find "Http\Discovery\HttpClientDiscovery::find();" "php-http/guzzle6-adapter:^2.0.1"
               # Test that we find a client with Symfony and Guzzle PSR-7
               - install_test will-find "Http\Discovery\HttpClientDiscovery::find();" "symfony/http-client:5.* php-http/httplug php-http/message-factory guzzlehttp/psr7:1.* http-interop/http-factory-guzzle"
               # We should fail if we dont have php-http/message-factory or PSR-17
@@ -69,6 +71,10 @@ matrix:
               - install_test will-find "Http\Discovery\HttpClientDiscovery::find();" "php-http/client-common:2.* php-http/message:1.8.* symfony/http-client:4.* php-http/guzzle6-adapter"
               # Test that we find an async client with Symfony and Guzzle
               - install_test will-find "Http\Discovery\HttpAsyncClientDiscovery::find();" "php-http/client-common:2.* php-http/message:1.8.* symfony/http-client:4.* php-http/guzzle6-adapter"
+              # Test that we find PSR-18 Guzzle 6
+              - install_test will-find "Http\Discovery\Psr18ClientDiscovery::find();" "php-http/guzzle6-adapter:^2.0.1"
+              # Test that we find PSR-18 Guzzle 7
+              - install_test will-find "Http\Discovery\Psr18ClientDiscovery::find();" "guzzlehttp/guzzle:^7.0.1"
 
 before_install:
     - if [[ $COVERAGE != true ]]; then phpenv config-rm xdebug.ini || true; fi
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a7bc447..1eba516 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Added
+
+- Support discovering PSR-18 factories of `guzzlehttp/guzzle` 7+
+
 ## 1.8.0 - 2020-06-14
 
 ### Added
diff --git a/composer.json b/composer.json
index 7a8e424..bca83c8 100644
--- a/composer.json
+++ b/composer.json
@@ -40,7 +40,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.7-dev"
+            "dev-master": "1.9-dev"
         }
     },
     "conflict": {
diff --git a/src/Strategy/CommonClassesStrategy.php b/src/Strategy/CommonClassesStrategy.php
index 383c7fc..ceff827 100644
--- a/src/Strategy/CommonClassesStrategy.php
+++ b/src/Strategy/CommonClassesStrategy.php
@@ -26,6 +26,7 @@
 use Http\Message\StreamFactory\SlimStreamFactory;
 use Http\Message\UriFactory\SlimUriFactory;
 use Slim\Http\Request as SlimRequest;
+use GuzzleHttp\Client as GuzzleHttp;
 use Http\Adapter\Guzzle6\Client as Guzzle6;
 use Http\Adapter\Guzzle5\Client as Guzzle5;
 use Http\Client\Curl\Client as Curl;
@@ -95,6 +96,10 @@ final class CommonClassesStrategy implements DiscoveryStrategy
                 'class' => [self::class, 'symfonyPsr18Instantiate'],
                 'condition' => [SymfonyPsr18::class, Psr17RequestFactory::class],
             ],
+            [
+                'class' => GuzzleHttp::class,
+                'condition' => GuzzleHttp::class,
+            ],
             [
                 'class' => [self::class, 'buzzInstantiate'],
                 'condition' => [\Buzz\Client\FileGetContents::class, \Buzz\Message\ResponseBuilder::class],
@@ -108,27 +113,43 @@ final class CommonClassesStrategy implements DiscoveryStrategy
     public static function getCandidates($type)
     {
         if (Psr18Client::class === $type) {
-            $candidates = self::$classes[PSR18Client::class];
+            return self::getPsr18Candidates();
+        }
+
+        return self::$classes[$type] ?? [];
+    }
+
+    /**
+     * @return array The return value is always an array with zero or more elements. Each
+     *               element is an array with two keys ['class' => string, 'condition' => mixed].
+     */
+    private static function getPsr18Candidates()
+    {
+        $candidates = [];
 
-            // HTTPlug 2.0 clients implements PSR18Client too.
-            foreach (self::$classes[HttpClient::class] as $c) {
-                try {
-                    if (is_subclass_of($c['class'], Psr18Client::class)) {
-                        $candidates[] = $c;
-                    }
-                } catch (\Throwable $e) {
-                    trigger_error(sprintf('Got exception "%s (%s)" while checking if a PSR-18 Client is available', get_class($e), $e->getMessage()), E_USER_WARNING);
+        // Guzzle 6 does not implement the PSR-18 client interface, but Guzzle 7 does.
+        foreach (self::$classes[Psr18Client::class] ?? [] as $c) {
+            if (GuzzleHttp::class === $c['class']) {
+                if (defined('GuzzleHttp\ClientInterface::MAJOR_VERSION')) {
+                    $candidates[] = $c;
                 }
+            } else {
+                $candidates[] = $c;
             }
-
-            return $candidates;
         }
 
-        if (isset(self::$classes[$type])) {
-            return self::$classes[$type];
+        // HTTPlug 2.0 clients implements PSR18Client too.
+        foreach (self::$classes[HttpClient::class] as $c) {
+            try {
+                if (is_subclass_of($c['class'], Psr18Client::class)) {
+                    $candidates[] = $c;
+                }
+            } catch (\Throwable $e) {
+                trigger_error(sprintf('Got exception "%s (%s)" while checking if a PSR-18 Client is available', get_class($e), $e->getMessage()), E_USER_WARNING);
+            }
         }
 
-        return [];
+        return $candidates;
     }
 
     public static function buzzInstantiate()