diff --git a/src/Symfony/Component/Console/Helper/QuestionHelper.php b/src/Symfony/Component/Console/Helper/QuestionHelper.php
index af4d0b9cca45..cccaeb024888 100644
--- a/src/Symfony/Component/Console/Helper/QuestionHelper.php
+++ b/src/Symfony/Component/Console/Helper/QuestionHelper.php
@@ -264,7 +264,7 @@ private function autocomplete(OutputInterface $output, Question $question, $inpu
             } elseif ("\177" === $c) { // Backspace Character
                 if (0 === $numMatches && 0 !== $i) {
                     --$i;
-                    $fullChoice = substr($fullChoice, 0, -1);
+                    $fullChoice = self::substr($fullChoice, 0, -1);
                     // Move cursor backwards
                     $output->write("\033[1D");
                 }
@@ -278,7 +278,7 @@ private function autocomplete(OutputInterface $output, Question $question, $inpu
                 }
 
                 // Pop the last character off the end of our string
-                $ret = substr($ret, 0, $i);
+                $ret = self::substr($ret, 0, $i);
             } elseif ("\033" === $c) {
                 // Did we read an escape sequence?
                 $c .= fread($inputStream, 2);
@@ -304,7 +304,7 @@ private function autocomplete(OutputInterface $output, Question $question, $inpu
                         $remainingCharacters = substr($ret, \strlen(trim($this->mostRecentlyEnteredValue($fullChoice))));
                         $output->write($remainingCharacters);
                         $fullChoice .= $remainingCharacters;
-                        $i = \strlen($fullChoice);
+                        $i = self::strlen($fullChoice);
                     }
 
                     if ("\n" === $c) {
diff --git a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
index 02cc6ce7e024..2e91d49feeca 100644
--- a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
+++ b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
@@ -175,19 +175,20 @@ public function testAskWithAutocomplete()
         // Acm<NEWLINE>
         // Ac<BACKSPACE><BACKSPACE>s<TAB>Test<NEWLINE>
         // <NEWLINE>
-        // <UP ARROW><UP ARROW><NEWLINE>
-        // <UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><TAB>Test<NEWLINE>
+        // <UP ARROW><UP ARROW><UP ARROW><NEWLINE>
+        // <UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><TAB>Test<NEWLINE>
         // <DOWN ARROW><NEWLINE>
         // S<BACKSPACE><BACKSPACE><DOWN ARROW><DOWN ARROW><NEWLINE>
         // F00<BACKSPACE><BACKSPACE>oo<TAB><NEWLINE>
-        $inputStream = $this->getInputStream("Acm\nAc\177\177s\tTest\n\n\033[A\033[A\n\033[A\033[A\033[A\033[A\033[A\tTest\n\033[B\nS\177\177\033[B\033[B\nF00\177\177oo\t\n");
+        // F⭐<TAB><BACKSPACE><BACKSPACE>⭐<TAB><NEWLINE>
+        $inputStream = $this->getInputStream("Acm\nAc\177\177s\tTest\n\n\033[A\033[A\033[A\n\033[A\033[A\033[A\033[A\033[A\033[A\033[A\tTest\n\033[B\nS\177\177\033[B\033[B\nF00\177\177oo\t\nF⭐\t\177\177⭐\t\n");
 
         $dialog = new QuestionHelper();
         $helperSet = new HelperSet([new FormatterHelper()]);
         $dialog->setHelperSet($helperSet);
 
         $question = new Question('Please select a bundle', 'FrameworkBundle');
-        $question->setAutocompleterValues(['AcmeDemoBundle', 'AsseticBundle', 'SecurityBundle', 'FooBundle']);
+        $question->setAutocompleterValues(['AcmeDemoBundle', 'AsseticBundle', 'SecurityBundle', 'FooBundle', 'F⭐Y']);
 
         $this->assertEquals('AcmeDemoBundle', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
         $this->assertEquals('AsseticBundleTest', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
@@ -197,6 +198,7 @@ public function testAskWithAutocomplete()
         $this->assertEquals('AcmeDemoBundle', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
         $this->assertEquals('AsseticBundle', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
         $this->assertEquals('FooBundle', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
+        $this->assertEquals('F⭐Y', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
     }
 
     public function testAskWithAutocompleteWithNonSequentialKeys()
@@ -680,12 +682,13 @@ public function testLegacyAskWithAutocomplete()
         // Acm<NEWLINE>
         // Ac<BACKSPACE><BACKSPACE>s<TAB>Test<NEWLINE>
         // <NEWLINE>
-        // <UP ARROW><UP ARROW><NEWLINE>
-        // <UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><TAB>Test<NEWLINE>
+        // <UP ARROW><UP ARROW><UP ARROW><NEWLINE>
+        // <UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><UP ARROW><TAB>Test<NEWLINE>
         // <DOWN ARROW><NEWLINE>
         // S<BACKSPACE><BACKSPACE><DOWN ARROW><DOWN ARROW><NEWLINE>
         // F00<BACKSPACE><BACKSPACE>oo<TAB><NEWLINE>
-        $inputStream = $this->getInputStream("Acm\nAc\177\177s\tTest\n\n\033[A\033[A\n\033[A\033[A\033[A\033[A\033[A\tTest\n\033[B\nS\177\177\033[B\033[B\nF00\177\177oo\t\n");
+        // F⭐<TAB><BACKSPACE><BACKSPACE>⭐<TAB><NEWLINE>
+        $inputStream = $this->getInputStream("Acm\nAc\177\177s\tTest\n\n\033[A\033[A\033[A\n\033[A\033[A\033[A\033[A\033[A\033[A\033[A\tTest\n\033[B\nS\177\177\033[B\033[B\nF00\177\177oo\t\nF⭐\t⭐\t\n");
 
         $dialog = new QuestionHelper();
         $dialog->setInputStream($inputStream);
@@ -693,7 +696,7 @@ public function testLegacyAskWithAutocomplete()
         $dialog->setHelperSet($helperSet);
 
         $question = new Question('Please select a bundle', 'FrameworkBundle');
-        $question->setAutocompleterValues(['AcmeDemoBundle', 'AsseticBundle', 'SecurityBundle', 'FooBundle']);
+        $question->setAutocompleterValues(['AcmeDemoBundle', 'AsseticBundle', 'SecurityBundle', 'FooBundle', 'F⭐Y']);
 
         $this->assertEquals('AcmeDemoBundle', $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
         $this->assertEquals('AsseticBundleTest', $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
@@ -703,6 +706,7 @@ public function testLegacyAskWithAutocomplete()
         $this->assertEquals('AcmeDemoBundle', $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
         $this->assertEquals('AsseticBundle', $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
         $this->assertEquals('FooBundle', $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
+        $this->assertEquals('F⭐Y', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
     }
 
     /**