diff --git a/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/CollectionRegionCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/CollectionRegionCommand.php
index 33f003a19a..1c75ccccac 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/CollectionRegionCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/CollectionRegionCommand.php
@@ -116,7 +116,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 )
             );
 
-            return;
+            return 0;
         }
 
         if ($input->getOption('all')) {
@@ -124,7 +124,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             $cache->evictEntityRegions();
 
-            return;
+            return 0;
         }
 
         if ($ownerId) {
@@ -138,10 +138,12 @@ protected function execute(InputInterface $input, OutputInterface $output)
             );
             $cache->evictCollection($ownerClass, $assoc, $ownerId);
 
-            return;
+            return 0;
         }
 
         $ui->comment(sprintf('Clearing second-level cache for collection <info>"%s#%s"</info>', $ownerClass, $assoc));
         $cache->evictCollectionRegion($ownerClass, $assoc);
+
+        return 0;
     }
 }
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/EntityRegionCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/EntityRegionCommand.php
index 67a73093fc..c246910c14 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/EntityRegionCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/EntityRegionCommand.php
@@ -108,7 +108,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             $ui->comment(sprintf('Flushing cache provider configured for entity named <info>"%s"</info>', $entityClass));
 
-            return;
+            return 0;
         }
 
         if ($input->getOption('all')) {
@@ -116,7 +116,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             $cache->evictEntityRegions();
 
-            return;
+            return 0;
         }
 
         if ($entityId) {
@@ -129,10 +129,12 @@ protected function execute(InputInterface $input, OutputInterface $output)
             );
             $cache->evictEntity($entityClass, $entityId);
 
-            return;
+            return 0;
         }
 
         $ui->comment(sprintf('Clearing second-level cache for entity <info>"%s"</info>', $entityClass));
         $cache->evictEntityRegion($entityClass);
+
+        return 0;
     }
 }
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/QueryRegionCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/QueryRegionCommand.php
index f1578bc641..36ffa12503 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/QueryRegionCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/ClearCache/QueryRegionCommand.php
@@ -112,7 +112,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 )
             );
 
-            return;
+            return 0;
         }
 
         if ($input->getOption('all')) {
@@ -120,10 +120,12 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             $cache->evictQueryRegions();
 
-            return;
+            return 0;
         }
 
         $ui->comment(sprintf('Clearing second-level cache query region named <info>"%s"</info>', $name));
         $cache->evictQueryRegion($name);
+
+        return 0;
     }
 }
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/ConvertDoctrine1SchemaCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/ConvertDoctrine1SchemaCommand.php
index b6b43bf8e0..112efb9642 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/ConvertDoctrine1SchemaCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/ConvertDoctrine1SchemaCommand.php
@@ -127,6 +127,8 @@ protected function execute(InputInterface $input, OutputInterface $output)
         $numSpaces = $input->getOption('num-spaces');
 
         $this->convertDoctrine1Schema($fromPaths, $destPath, $toType, $numSpaces, $extend, $output);
+
+        return 0;
     }
 
     /**
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/ConvertMappingCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/ConvertMappingCommand.php
index f675664114..8de2b84a9e 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/ConvertMappingCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/ConvertMappingCommand.php
@@ -167,6 +167,8 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $destPath
             )
         );
+
+        return 0;
     }
 
     /**
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/GenerateEntitiesCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/GenerateEntitiesCommand.php
index 063cb244ce..828c1432db 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/GenerateEntitiesCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/GenerateEntitiesCommand.php
@@ -112,7 +112,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         if (empty($metadatas)) {
             $ui->success('No Metadata Classes to process.');
-            return;
+            return 0;
         }
 
         $entityGenerator = new EntityGenerator();
@@ -138,5 +138,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
         // Outputting information message
         $ui->newLine();
         $ui->success(sprintf('Entity classes generated to "%s"', $destPath));
+
+        return 0;
     }
 }
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/GenerateProxiesCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/GenerateProxiesCommand.php
index 3755be5805..2cace34345 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/GenerateProxiesCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/GenerateProxiesCommand.php
@@ -91,7 +91,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         if (empty($metadatas)) {
             $ui->success('No Metadata Classes to process.');
-            return;
+            return 0;
         }
 
         foreach ($metadatas as $metadata) {
@@ -104,5 +104,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
         // Outputting information message
         $ui->newLine();
         $ui->text(sprintf('Proxy classes generated to "<info>%s</info>"', $destPath));
+
+        return 0;
     }
 }
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/GenerateRepositoriesCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/GenerateRepositoriesCommand.php
index 941944ff52..666ae7867b 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/GenerateRepositoriesCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/GenerateRepositoriesCommand.php
@@ -84,7 +84,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         if (empty($metadatas)) {
             $ui->success('No Metadata Classes to process.');
-            return;
+            return 0;
         }
 
         $numRepositories = 0;
@@ -104,11 +104,13 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         if ($numRepositories === 0) {
             $ui->text('No Repository classes were found to be processed.');
-            return;
+            return 0;
         }
 
         // Outputting information message
         $ui->newLine();
         $ui->text(sprintf('Repository classes generated to "<info>%s</info>"', $destPath));
+
+        return 0;
     }
 }
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/RunDqlCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/RunDqlCommand.php
index 4e6b69bb42..7f4069202b 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/RunDqlCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/RunDqlCommand.php
@@ -104,11 +104,13 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         if ($input->getOption('show-sql')) {
             $ui->text($query->getSQL());
-            return;
+            return 0;
         }
 
         $resultSet = $query->execute([], constant($hydrationMode));
 
         $ui->text(Debug::dump($resultSet, $input->getOption('depth'), true, false));
+
+        return 0;
     }
 }