diff --git a/src/Composer/InstalledVersions.php b/src/Composer/InstalledVersions.php
index 9809a2190..7c5502ca4 100644
--- a/src/Composer/InstalledVersions.php
+++ b/src/Composer/InstalledVersions.php
@@ -20,7 +20,7 @@ use Composer\Semver\VersionParser;
  *
  * See also https://getcomposer.org/doc/07-runtime.md#installed-versions
  *
- * To require it's presence, you can require `composer-runtime-api ^2.0`
+ * To require its presence, you can require `composer-runtime-api ^2.0`
  */
 class InstalledVersions
 {
diff --git a/src/Composer/Repository/RepositoryManager.php b/src/Composer/Repository/RepositoryManager.php
index 717fce4ee..12123ce7b 100644
--- a/src/Composer/Repository/RepositoryManager.php
+++ b/src/Composer/Repository/RepositoryManager.php
@@ -55,7 +55,7 @@ class RepositoryManager
     }
 
     /**
-     * Searches for a package by it's name and version in managed repositories.
+     * Searches for a package by its name and version in managed repositories.
      *
      * @param string                                                 $name       package name
      * @param string|\Composer\Semver\Constraint\ConstraintInterface $constraint package version or version constraint to match against
diff --git a/src/Composer/Util/Filesystem.php b/src/Composer/Util/Filesystem.php
index 69f097958..5f99d8d30 100644
--- a/src/Composer/Util/Filesystem.php
+++ b/src/Composer/Util/Filesystem.php
@@ -514,7 +514,7 @@ class Filesystem
 
     /**
      * Returns size of a file or directory specified by path. If a directory is
-     * given, it's size will be computed recursively.
+     * given, its size will be computed recursively.
      *
      * @param  string            $path Path to the file or directory
      * @throws \RuntimeException
diff --git a/tests/Composer/Test/Fixtures/functional/installed-versions2/vendor/composer/InstalledVersions.php b/tests/Composer/Test/Fixtures/functional/installed-versions2/vendor/composer/InstalledVersions.php
index fc9dc216c..0b38bb7b9 100644
--- a/tests/Composer/Test/Fixtures/functional/installed-versions2/vendor/composer/InstalledVersions.php
+++ b/tests/Composer/Test/Fixtures/functional/installed-versions2/vendor/composer/InstalledVersions.php
@@ -18,7 +18,7 @@ use Composer\Semver\VersionParser;
 /**
  * This class is copied in every Composer installed project and available to all
  *
- * To require it's presence, you can require `composer-runtime-api ^2.0`
+ * To require its presence, you can require `composer-runtime-api ^2.0`
  */
 class InstalledVersions
 {
diff --git a/tests/Composer/Test/Fixtures/installer/update-reference.test b/tests/Composer/Test/Fixtures/installer/update-reference.test
index 7836cbf5a..185b72013 100644
--- a/tests/Composer/Test/Fixtures/installer/update-reference.test
+++ b/tests/Composer/Test/Fixtures/installer/update-reference.test
@@ -1,5 +1,5 @@
 --TEST--
-Updates a dev package forcing it's reference
+Updates a dev package forcing its reference
 --COMPOSER--
 {
     "repositories": [