diff --git a/src/Mutator/Unwrap/UnwrapUcWords.php b/src/Mutator/Unwrap/UnwrapUcWords.php
new file mode 100644
index 000000000..894d0692b
--- /dev/null
+++ b/src/Mutator/Unwrap/UnwrapUcWords.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Mutator\Unwrap;
+
+use PhpParser\Node;
+
+/**
+ * @internal
+ */
+final class UnwrapUcWords extends AbstractUnwrapMutator
+{
+    protected function getFunctionName(): string
+    {
+        return 'ucwords';
+    }
+
+    protected function getParameterIndexes(Node $node): \Generator
+    {
+        yield 0;
+    }
+}
diff --git a/src/Mutator/Util/MutatorProfile.php b/src/Mutator/Util/MutatorProfile.php
index 0fec1c122..04f1e01a1 100644
--- a/src/Mutator/Util/MutatorProfile.php
+++ b/src/Mutator/Util/MutatorProfile.php
@@ -228,6 +228,7 @@ final class MutatorProfile
         Mutator\Unwrap\UnwrapStrToUpper::class,
         Mutator\Unwrap\UnwrapTrim::class,
         Mutator\Unwrap\UnwrapUcFirst::class,
+        Mutator\Unwrap\UnwrapUcWords::class,
     ];
 
     public const DEFAULT = [
@@ -391,5 +392,6 @@ final class MutatorProfile
         'UnwrapStrToUpper' => Mutator\Unwrap\UnwrapStrToUpper::class,
         'UnwrapTrim' => Mutator\Unwrap\UnwrapTrim::class,
         'UnwrapUcFirst' => Mutator\Unwrap\UnwrapUcFirst::class,
+        'UnwrapUcWords' => Mutator\Unwrap\UnwrapUcWords::class,
     ];
 }
diff --git a/tests/Mutator/Unwrap/UnwrapUcWordsTest.php b/tests/Mutator/Unwrap/UnwrapUcWordsTest.php
new file mode 100644
index 000000000..58caa8dcd
--- /dev/null
+++ b/tests/Mutator/Unwrap/UnwrapUcWordsTest.php
@@ -0,0 +1,206 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Tests\Mutator\Unwrap;
+
+use Infection\Tests\Mutator\AbstractMutatorTestCase;
+
+/**
+ * @internal
+ */
+final class UnwrapUcWordsTest extends AbstractMutatorTestCase
+{
+    /**
+     * @dataProvider provideMutationCases
+     */
+    public function test_mutator($input, $expected = null): void
+    {
+        $this->doTest($input, $expected);
+    }
+
+    public function provideMutationCases(): \Generator
+    {
+        yield 'It mutates correctly when provided with a string' => [
+            <<<'PHP'
+<?php
+
+$a = ucwords('good afternoon!');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'good afternoon!';
+PHP
+        ];
+
+        yield 'It mutates correctly when provided with a constant' => [
+            <<<'PHP'
+<?php
+
+$a = ucwords(\Class_With_Const::Const);
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = \Class_With_Const::Const;
+PHP
+        ];
+
+        yield 'It mutates correctly when a backslash is in front of ucwords' => [
+            <<<'PHP'
+<?php
+
+$a = \ucwords('good afternoon!');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'good afternoon!';
+PHP
+        ];
+
+        yield 'It mutates correctly within if statements' => [
+            <<<'PHP'
+<?php
+
+$a = 'good afternoon!';
+if (ucwords($a) === $a) {
+    return true;
+}
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'good afternoon!';
+if ($a === $a) {
+    return true;
+}
+PHP
+        ];
+
+        yield 'It mutates correctly when ucwords is wrongly capitalized' => [
+            <<<'PHP'
+<?php
+
+$a = uCwOrDs('good afternoon!');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'good afternoon!';
+PHP
+        ];
+
+        yield 'It mutates correctly when ucwords uses another function as input' => [
+            <<<'PHP'
+<?php
+
+$a = ucwords($foo->bar());
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = $foo->bar();
+PHP
+        ];
+
+        yield 'It mutates correctly when provided with a more complex situation' => [
+            <<<'PHP'
+<?php
+
+$a = ucwords(array_reduce($words, function (string $carry, string $item) {
+    return $carry . substr($item, 0, 1);
+}));
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = array_reduce($words, function (string $carry, string $item) {
+    return $carry . substr($item, 0, 1);
+});
+PHP
+        ];
+
+        yield 'It does not mutate other calls' => [
+            <<<'PHP'
+<?php
+
+$a = strtolower('Good Afternoon!');
+PHP
+        ];
+
+        yield 'It does not mutate functions named ucwords' => [
+            <<<'PHP'
+<?php
+
+function ucwords($string)
+{
+}
+PHP
+        ];
+
+        yield 'It does not break when provided with a variable function name' => [
+            <<<'PHP'
+<?php
+
+$a = 'ucwords';
+
+$b = $a('FooBar');
+PHP
+            ,
+        ];
+
+        yield 'It does not break when ucwords uses a delimiter parameter' => [
+            <<<'PHP'
+<?php
+
+$a = ucwords('good|afternoon|world', '|');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'good|afternoon|world';
+PHP
+        ];
+    }
+}