diff --git a/generator/lib/builder/om/PHP5PeerBuilder.php b/generator/lib/builder/om/PHP5PeerBuilder.php
index bd0fe2b16..30f9abe57 100644
--- a/generator/lib/builder/om/PHP5PeerBuilder.php
+++ b/generator/lib/builder/om/PHP5PeerBuilder.php
@@ -1164,7 +1164,7 @@ public static function getPrimaryKeyFromRow(\$row, \$startcol = 0)
             if ($table->hasCompositePrimaryKey()) {
                 $script .= "
 
-        return array(" . implode($pks, ', '). ");";
+        return array(" . implode(', ', $pks). ");";
             } else {
                 $script .= "
 
diff --git a/generator/lib/builder/om/QueryBuilder.php b/generator/lib/builder/om/QueryBuilder.php
index 30c0c44cc..46cae0f98 100644
--- a/generator/lib/builder/om/QueryBuilder.php
+++ b/generator/lib/builder/om/QueryBuilder.php
@@ -395,10 +395,10 @@ protected function addFindPk(&$script)
             }
             $pkType = 'array';
             $pkDescription = "
-                         A Primary key composition: ".'['. join($colNames, ', ') . ']';
+                         A Primary key composition: ".'['. join(', ', $colNames) . ']';
             $script .= "
      * <code>
-     * \$obj = \$c->findPk(array(" . join($examplePk, ', ') . "), \$con);";
+     * \$obj = \$c->findPk(array(" . join(', ', $examplePk) . "), \$con);";
         } else {
             $pkType = 'mixed';
             $script .= "
diff --git a/generator/lib/model/Database.php b/generator/lib/model/Database.php
index cd48d033a..8d2a4089f 100644
--- a/generator/lib/model/Database.php
+++ b/generator/lib/model/Database.php
@@ -390,7 +390,7 @@ public function addTable($data)
             $this->tablesByName[$tbl->getName()] = $tbl;
             $this->tablesByLowercaseName[strtolower($tbl->getName())] = $tbl;
             $this->tablesByPhpName[$tbl->getPhpName()] = $tbl;
-            if (strpos($tbl->getNamespace(), '\\') === 0) {
+            if (strpos((string) $tbl->getNamespace(), '\\') === 0) {
                 $tbl->setNamespace(substr($tbl->getNamespace(), 1));
             } elseif ($namespace = $this->getNamespace()) {
                 if ($tbl->getNamespace() === null) {
diff --git a/generator/lib/model/XMLElement.php b/generator/lib/model/XMLElement.php
index 1a0959fd9..31f46a580 100644
--- a/generator/lib/model/XMLElement.php
+++ b/generator/lib/model/XMLElement.php
@@ -85,7 +85,7 @@ protected function booleanValue($val)
         if (is_numeric($val)) {
             return (bool) $val;
         } else {
-            return (in_array(strtolower($val), array('true', 't', 'y', 'yes'), true) ? true : false);
+            return (in_array(strtolower((string) $val), array('true', 't', 'y', 'yes'), true) ? true : false);
         }
     }
 
diff --git a/runtime/lib/collection/PropelCollection.php b/runtime/lib/collection/PropelCollection.php
index 79d7cc0f8..26637b5f0 100644
--- a/runtime/lib/collection/PropelCollection.php
+++ b/runtime/lib/collection/PropelCollection.php
@@ -359,7 +359,7 @@ public function diff(PropelCollection $collection)
     /**
      * @return string
      */
-    public function serialize()
+    public function serialize(): string
     {
         $repr = array(
             'data'   => $this->getArrayCopy(),
@@ -371,10 +371,8 @@ public function serialize()
 
     /**
      * @param string $data
-     *
-     * @return void
      */
-    public function unserialize($data)
+    public function unserialize($data): void
     {
         $repr = unserialize($data);
         $this->exchangeArray($repr['data']);
@@ -389,7 +387,7 @@ public function unserialize($data)
      *
      * @return ArrayIterator
      */
-    public function getIterator()
+    public function getIterator(): Iterator
     {
         $this->iterator = new ArrayIterator($this);
 
diff --git a/runtime/lib/collection/PropelObjectCollection.php b/runtime/lib/collection/PropelObjectCollection.php
index 22e6784cb..c67587421 100644
--- a/runtime/lib/collection/PropelObjectCollection.php
+++ b/runtime/lib/collection/PropelObjectCollection.php
@@ -134,10 +134,8 @@ public function fromArray($arr)
      *    'Book_1' => $book1,
      *   )
      * </code>
-     *
-     * @return array
      */
-    public function getArrayCopy($keyColumn = null, $usePrefix = false)
+    public function getArrayCopy($keyColumn = null, $usePrefix = false): array
     {
         if (null === $keyColumn && false === $usePrefix) {
             return parent::getArrayCopy();
diff --git a/runtime/lib/config/PropelConfiguration.php b/runtime/lib/config/PropelConfiguration.php
index cc5238be8..777ecdae4 100644
--- a/runtime/lib/config/PropelConfiguration.php
+++ b/runtime/lib/config/PropelConfiguration.php
@@ -44,9 +44,8 @@ public function __construct(array $parameters = array())
      * @see       http://www.php.net/ArrayAccess
      *
      * @param  integer $offset
-     * @return boolean
      */
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return array_key_exists($offset, $this->parameters);
     }
@@ -57,7 +56,7 @@ public function offsetExists($offset)
      * @param integer $offset
      * @param mixed   $value
      */
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         $this->parameters[$offset] = $value;
         $this->isFlattened = false;
@@ -69,7 +68,7 @@ public function offsetSet($offset, $value)
      * @param  integer $offset
      * @return array
      */
-    public function offsetGet($offset)
+    public function offsetGet($offset): array
     {
         return $this->parameters[$offset];
     }
diff --git a/runtime/lib/connection/DebugPDOStatement.php b/runtime/lib/connection/DebugPDOStatement.php
index 3f0ca3715..e70520b3c 100644
--- a/runtime/lib/connection/DebugPDOStatement.php
+++ b/runtime/lib/connection/DebugPDOStatement.php
@@ -82,9 +82,8 @@ public function getExecutedQueryString()
      * Overridden for query counting and logging.
      *
      * @param  string  $input_parameters
-     * @return boolean
      */
-    public function execute($input_parameters = null)
+    public function execute($input_parameters = null): bool
     {
         $debug	= $this->pdo->getDebugSnapshot();
         $return	= parent::execute($input_parameters);
@@ -104,10 +103,8 @@ public function execute($input_parameters = null)
      * @param integer $pos   Parameter identifier (for determining what to replace in the query).
      * @param mixed   $value The value to bind to the parameter.
      * @param integer $type  Explicit data type for the parameter using the PDO::PARAM_* constants. Defaults to PDO::PARAM_STR.
-     *
-     * @return boolean
      */
-    public function bindValue($pos, $value, $type = PDO::PARAM_STR)
+    public function bindValue($pos, $value, $type = PDO::PARAM_STR): bool
     {
         $debug    = $this->pdo->getDebugSnapshot();
         $typestr  = isset(self::$typeMap[$type]) ? self::$typeMap[$type] : '(default)';
@@ -133,10 +130,8 @@ public function bindValue($pos, $value, $type = PDO::PARAM_STR)
      * @param integer $type           Explicit data type for the parameter using the PDO::PARAM_* constants. Defaults to PDO::PARAM_STR.
      * @param integer $length         Length of the data type. To indicate that a parameter is an OUT parameter from a stored procedure, you must explicitly set the length.
      * @param mixed   $driver_options
-     *
-     * @return boolean
      */
-    public function bindParam($pos, &$value, $type = PDO::PARAM_STR, $length = 0, $driver_options = null)
+    public function bindParam($pos, &$value, $type = PDO::PARAM_STR, $length = 0, $driver_options = null): bool
     {
         $debug    = $this->pdo->getDebugSnapshot();
         $typestr  = isset(self::$typeMap[$type]) ? self::$typeMap[$type] : '(default)';
diff --git a/runtime/lib/connection/PropelPDO.php b/runtime/lib/connection/PropelPDO.php
index ba184d669..15c78774d 100644
--- a/runtime/lib/connection/PropelPDO.php
+++ b/runtime/lib/connection/PropelPDO.php
@@ -224,10 +224,8 @@ public function isCommitable()
 
     /**
      * Overrides PDO::beginTransaction() to prevent errors due to already-in-progress transaction.
-     *
-     * @return boolean
      */
-    public function beginTransaction()
+    public function beginTransaction(): bool
     {
         $return = true;
         if (!$this->nestedTransactionCount) {
@@ -246,11 +244,9 @@ public function beginTransaction()
      * Overrides PDO::commit() to only commit the transaction if we are in the outermost
      * transaction nesting level.
      *
-     * @return boolean
-     *
      * @throws PropelException
      */
-    public function commit()
+    public function commit(): bool
     {
         $return = true;
         $opcount = $this->nestedTransactionCount;
@@ -279,7 +275,7 @@ public function commit()
      *
      * @return boolean Whether operation was successful.
      */
-    public function rollBack()
+    public function rollBack(): bool
     {
         $return = true;
         $opcount = $this->nestedTransactionCount;
@@ -301,11 +297,11 @@ public function rollBack()
     }
 
     /**
-    * Rollback the whole transaction, even if this is a nested rollback
-    * and reset the nested transaction count to 0.
+     * Rollback the whole transaction, even if this is a nested rollback
+     * and reset the nested transaction count to 0.
      *
-    * @return    boolean  Whether operation was successful.
-    */
+     * @return    boolean  Whether operation was successful.
+     */
     public function forceRollBack()
     {
         $return = true;
@@ -334,10 +330,8 @@ public function forceRollBack()
      *
      * @param integer $attribute The attribute to set (e.g. PropelPDO::PROPEL_ATTR_CACHE_PREPARES).
      * @param mixed   $value     The attribute value.
-     *
-     * @return void
      */
-    public function setAttribute($attribute, $value)
+    public function setAttribute($attribute, $value): bool
     {
         switch ($attribute) {
             case self::PROPEL_ATTR_CACHE_PREPARES:
@@ -347,8 +341,9 @@ public function setAttribute($attribute, $value)
                 $this->connectionName = $value;
                 break;
             default:
-                parent::setAttribute($attribute, $value);
+                return parent::setAttribute($attribute, $value);
         }
+        return true;
     }
 
     /**
@@ -415,9 +410,8 @@ public function prepare($sql, $driver_options = array())
      * Overrides PDO::exec() to log queries when required
      *
      * @param  string  $sql
-     * @return integer
      */
-    public function exec($sql)
+    public function exec($sql): int
     {
         if ($this->useDebug) {
             $debug = $this->getDebugSnapshot();
@@ -657,7 +651,7 @@ public function getDebugSnapshot()
                 'microtime'             => microtime(true),
                 'memory_get_usage'      => memory_get_usage($this->getLoggingConfig('realmemoryusage', false)),
                 'memory_get_peak_usage' => memory_get_peak_usage($this->getLoggingConfig('realmemoryusage', false)),
-                );
+            );
         } else {
             throw new PropelException('Should not get debug snapshot when not debugging');
         }
diff --git a/runtime/lib/query/Criteria.php b/runtime/lib/query/Criteria.php
index 82e7fd028..f14ff2ea6 100644
--- a/runtime/lib/query/Criteria.php
+++ b/runtime/lib/query/Criteria.php
@@ -261,7 +261,7 @@ public function __construct($dbName = null)
      * Implementing SPL IteratorAggregate interface.  This allows
      * you to foreach () over a Criteria object.
      */
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new CriterionIterator($this);
     }
diff --git a/runtime/lib/query/ModelCriteria.php b/runtime/lib/query/ModelCriteria.php
index ac498c8ab..8cecbba5a 100644
--- a/runtime/lib/query/ModelCriteria.php
+++ b/runtime/lib/query/ModelCriteria.php
@@ -56,7 +56,7 @@ class ModelCriteria extends Criteria
      * Creates a new instance with the default capacity which corresponds to
      * the specified database.
      *
-     * @param string $dbName     The dabase name
+     * @param string $dbName     The database name
      * @param string $modelName  The phpName of a model, e.g. 'Book'
      * @param string $modelAlias The alias for the model in this query, e.g. 'b'
      */