diff --git a/src/Composer/DependencyResolver/SolverProblemsException.php b/src/Composer/DependencyResolver/SolverProblemsException.php
index 6014012a4..142895697 100644
--- a/src/Composer/DependencyResolver/SolverProblemsException.php
+++ b/src/Composer/DependencyResolver/SolverProblemsException.php
@@ -43,7 +43,7 @@ class SolverProblemsException extends \RuntimeException
         }
 
         if (strpos($text, 'could not be found') || strpos($text, 'no matching package found')) {
-            $text .= "\nPotential causes:\n - A typo in the package name\n - The package is not available in a stable-enough version according to your minimum-stability setting\n   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.\n\nRead <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.";
+            $text .= "\nPotential causes:\n - A typo in the package name\n - The package is not available in a stable-enough version according to your minimum-stability setting\n   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.\n - It's a private package and you forgot to add a custom repository to find it\n\nRead <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.";
         }
 
         if ($hasExtensionProblems) {
diff --git a/tests/Composer/Test/DependencyResolver/SolverTest.php b/tests/Composer/Test/DependencyResolver/SolverTest.php
index 9067c4abd..989c992f0 100644
--- a/tests/Composer/Test/DependencyResolver/SolverTest.php
+++ b/tests/Composer/Test/DependencyResolver/SolverTest.php
@@ -710,7 +710,8 @@ class SolverTest extends TestCase
             $msg .= "Potential causes:\n";
             $msg .= " - A typo in the package name\n";
             $msg .= " - The package is not available in a stable-enough version according to your minimum-stability setting\n";
-            $msg .= "   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.\n\n";
+            $msg .= "   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.\n";
+            $msg .= " - It's a private package and you forgot to add a custom repository to find it\n\n";
             $msg .= "Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.";
             $this->assertEquals($msg, $e->getMessage());
         }
diff --git a/tests/Composer/Test/Fixtures/installer/broken-deps-do-not-replace.test b/tests/Composer/Test/Fixtures/installer/broken-deps-do-not-replace.test
index fe6b00fff..db4ef23c0 100644
--- a/tests/Composer/Test/Fixtures/installer/broken-deps-do-not-replace.test
+++ b/tests/Composer/Test/Fixtures/installer/broken-deps-do-not-replace.test
@@ -34,6 +34,7 @@ Potential causes:
  - A typo in the package name
  - The package is not available in a stable-enough version according to your minimum-stability setting
    see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.
+ - It's a private package and you forgot to add a custom repository to find it
 
 Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.
 
diff --git a/tests/Composer/Test/Fixtures/installer/solver-problems.test b/tests/Composer/Test/Fixtures/installer/solver-problems.test
index 605bd3cae..e0359a151 100644
--- a/tests/Composer/Test/Fixtures/installer/solver-problems.test
+++ b/tests/Composer/Test/Fixtures/installer/solver-problems.test
@@ -55,6 +55,7 @@ Potential causes:
  - A typo in the package name
  - The package is not available in a stable-enough version according to your minimum-stability setting
    see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.
+ - It's a private package and you forgot to add a custom repository to find it
 
 Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.