diff --git a/src/RequestParameterList/ArrayToListConverter.php b/src/RequestParameterList/ArrayToListConverter.php
index 9d05229..f7dfcbe 100644
--- a/src/RequestParameterList/ArrayToListConverter.php
+++ b/src/RequestParameterList/ArrayToListConverter.php
@@ -14,7 +14,11 @@ public static function convert(array $array): RequestParameterList
         $requestParameterList = new RequestParameterList();
 
         foreach ($array as $key => $value) {
-            $requestParameterList->add($key, $value);
+            if (is_array($value)) {
+                $value = implode(',', $value);
+            }
+
+            $requestParameterList->add($key, (string) $value);
         }
 
         return $requestParameterList;
diff --git a/src/RequestParameterList/RequestToListConverter.php b/src/RequestParameterList/RequestToListConverter.php
index 3dd7046..e1ea5f1 100644
--- a/src/RequestParameterList/RequestToListConverter.php
+++ b/src/RequestParameterList/RequestToListConverter.php
@@ -16,7 +16,11 @@ public static function convert(Request $request): RequestParameterList
         $requestParameterList = new RequestParameterList();
 
         foreach ($request->query->all() as $key => $value) {
-            $requestParameterList->add($key, $value);
+            if (is_array($value)) {
+                $value = implode(',', $value);
+            }
+
+            $requestParameterList->add($key, (string) $value);
         }
 
         return $requestParameterList;
diff --git a/tests/RequestParameterList/ArrayToListConverterTest.php b/tests/RequestParameterList/ArrayToListConverterTest.php
index 6c82c03..9cbe2ba 100644
--- a/tests/RequestParameterList/ArrayToListConverterTest.php
+++ b/tests/RequestParameterList/ArrayToListConverterTest.php
@@ -29,12 +29,39 @@ public function testConvertSimpleArray(): void
         $this->assertSame('6', $result->get('month'));
     }
 
-    public function testConvertNonStringValueThrowsTypeError(): void
+    public function testConvertIntegerValueToString(): void
     {
-        $this->expectException(\TypeError::class);
-
-        ArrayToListConverter::convert([
+        $result = ArrayToListConverter::convert([
             'size' => 25,
         ]);
+
+        $this->assertSame('25', $result->get('size'));
+    }
+
+    public function testConvertArrayValueToCommaSeparatedString(): void
+    {
+        $result = ArrayToListConverter::convert([
+            'tags' => ['foo', 'bar', 'baz'],
+        ]);
+
+        $this->assertSame('foo,bar,baz', $result->get('tags'));
+    }
+
+    public function testConvertFloatValueToString(): void
+    {
+        $result = ArrayToListConverter::convert([
+            'latitude' => 52.52,
+        ]);
+
+        $this->assertSame('52.52', $result->get('latitude'));
+    }
+
+    public function testConvertBooleanValueToString(): void
+    {
+        $result = ArrayToListConverter::convert([
+            'enabled' => true,
+        ]);
+
+        $this->assertSame('1', $result->get('enabled'));
     }
 }
diff --git a/tests/RequestParameterList/QueryStringToListConverterTest.php b/tests/RequestParameterList/QueryStringToListConverterTest.php
index 61de54a..f142739 100644
--- a/tests/RequestParameterList/QueryStringToListConverterTest.php
+++ b/tests/RequestParameterList/QueryStringToListConverterTest.php
@@ -48,11 +48,12 @@ public function testConvertQueryStringWithUrlEncodedValues(): void
         $this->assertSame('München', $result->get('city'));
     }
 
-    public function testConvertQueryStringWithArrayParametersThrowsTypeError(): void
+    public function testConvertQueryStringWithArrayParameters(): void
     {
-        $this->expectException(\TypeError::class);
+        $result = QueryStringToListConverter::convert('tags[]=foo&tags[]=bar');
 
-        QueryStringToListConverter::convert('tags[]=foo&tags[]=bar');
+        $this->assertTrue($result->has('tags'));
+        $this->assertSame('foo,bar', $result->get('tags'));
     }
 
     public function testConvertQueryStringWithMultipleParameters(): void
diff --git a/tests/RequestParameterList/RequestToListConverterTest.php b/tests/RequestParameterList/RequestToListConverterTest.php
index 285ac09..255a5fe 100644
--- a/tests/RequestParameterList/RequestToListConverterTest.php
+++ b/tests/RequestParameterList/RequestToListConverterTest.php
@@ -29,22 +29,22 @@ public function testConvertEmptyRequest(): void
         $this->assertSame([], $result->getList());
     }
 
-    public function testConvertRequestWithArrayQueryParameterThrowsTypeError(): void
+    public function testConvertRequestWithArrayQueryParameter(): void
     {
-        $this->expectException(\TypeError::class);
-
         $request = Request::create('/test', 'GET', ['tags' => ['foo', 'bar']]);
 
-        RequestToListConverter::convert($request);
+        $result = RequestToListConverter::convert($request);
+
+        $this->assertSame('foo,bar', $result->get('tags'));
     }
 
-    public function testConvertRequestWithIntegerQueryParameterThrowsTypeError(): void
+    public function testConvertRequestWithIntegerQueryParameter(): void
     {
-        $this->expectException(\TypeError::class);
-
         $request = Request::create('/test', 'GET', ['size' => 25]);
 
-        RequestToListConverter::convert($request);
+        $result = RequestToListConverter::convert($request);
+
+        $this->assertSame('25', $result->get('size'));
     }
 
     public function testConvertRequestWithMultipleParameters(): void