diff --git a/CHANGELOG.md b/CHANGELOG.md
index 77d5431d3..a750a16c4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,6 +57,11 @@
   * Fixed suggest output being very spammy, it now is only one line long and shows more rarely
   * Fixed conflict rules like e.g. >=5 from matching dev-master, as it is not normalized to 9999999-dev internally anymore
 
+### [1.10.13] 2020-09-09
+
+  * Fixed regressions with old version validation
+  * Fixed invalid root aliases not being reported
+
 ### [1.10.12] 2020-09-08
 
   * Fixed regressions with old version validation
@@ -951,6 +956,7 @@
 [2.0.0-alpha3]: https://github.com/composer/composer/compare/2.0.0-alpha2...2.0.0-alpha3
 [2.0.0-alpha2]: https://github.com/composer/composer/compare/2.0.0-alpha1...2.0.0-alpha2
 [2.0.0-alpha1]: https://github.com/composer/composer/compare/1.10.7...2.0.0-alpha1
+[1.10.13]: https://github.com/composer/composer/compare/1.10.12...1.10.13
 [1.10.12]: https://github.com/composer/composer/compare/1.10.11...1.10.12
 [1.10.11]: https://github.com/composer/composer/compare/1.10.10...1.10.11
 [1.10.10]: https://github.com/composer/composer/compare/1.10.9...1.10.10
diff --git a/composer.lock b/composer.lock
index 94cf637d9..433aa3422 100644
--- a/composer.lock
+++ b/composer.lock
@@ -83,16 +83,16 @@
         },
         {
             "name": "composer/semver",
-            "version": "3.1.0",
+            "version": "3.2.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/composer/semver.git",
-                "reference": "c64053b1543d7bc054883f0a78a86c4242ae315d"
+                "reference": "da7ce661431b17a71271cdf7f5437dc722133123"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/composer/semver/zipball/c64053b1543d7bc054883f0a78a86c4242ae315d",
-                "reference": "c64053b1543d7bc054883f0a78a86c4242ae315d",
+                "url": "https://api.github.com/repos/composer/semver/zipball/da7ce661431b17a71271cdf7f5437dc722133123",
+                "reference": "da7ce661431b17a71271cdf7f5437dc722133123",
                 "shasum": ""
             },
             "require": {
@@ -144,7 +144,7 @@
             "support": {
                 "irc": "irc://irc.freenode.org/composer",
                 "issues": "https://github.com/composer/semver/issues",
-                "source": "https://github.com/composer/semver/tree/main"
+                "source": "https://github.com/composer/semver/tree/3.2.0"
             },
             "funding": [
                 {
@@ -160,7 +160,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2020-09-08T20:59:47+00:00"
+            "time": "2020-09-09T09:39:19+00:00"
         },
         {
             "name": "composer/spdx-licenses",
diff --git a/src/Composer/Package/Loader/RootPackageLoader.php b/src/Composer/Package/Loader/RootPackageLoader.php
index ac3d8f433..fc2c2d834 100644
--- a/src/Composer/Package/Loader/RootPackageLoader.php
+++ b/src/Composer/Package/Loader/RootPackageLoader.php
@@ -186,6 +186,8 @@ class RootPackageLoader extends ArrayLoader
                     'alias' => $match[2],
                     'alias_normalized' => $this->versionParser->normalize($match[2], $reqVersion),
                 );
+            } elseif (strpos($reqVersion, ' as ') !== false) {
+                throw new \UnexpectedValueException('Invalid alias definition in "'.$reqName.'": "'.$reqVersion.'". Aliases should be in the form "exact-version as other-exact-version".');
             }
         }