diff --git a/src/Network/HTTPClient/Capability/ICanHandleHttpResponses.php b/src/Network/HTTPClient/Capability/ICanHandleHttpResponses.php
index e2db2f50fc..e8cc43a3c7 100644
--- a/src/Network/HTTPClient/Capability/ICanHandleHttpResponses.php
+++ b/src/Network/HTTPClient/Capability/ICanHandleHttpResponses.php
@@ -33,14 +33,14 @@ interface ICanHandleHttpResponses
 	 *
 	 * @return string The Return Code
 	 */
-	public function getReturnCode();
+	public function getReturnCode(): string;
 
 	/**
 	 * Returns the Content Type
 	 *
 	 * @return string the Content Type
 	 */
-	public function getContentType();
+	public function getContentType(): string;
 
 	/**
 	 * Returns the headers
@@ -51,7 +51,7 @@ interface ICanHandleHttpResponses
 	 *@see MessageInterface::getHeader()
 	 *
 	 */
-	public function getHeader(string $header);
+	public function getHeader(string $header): array;
 
 	/**
 	 * Returns all headers
@@ -59,7 +59,7 @@ interface ICanHandleHttpResponses
 	 *
 	 * @return string[][]
 	 */
-	public function getHeaders();
+	public function getHeaders(): array;
 
 	/**
 	 * Check if a specified header exists
@@ -69,7 +69,7 @@ interface ICanHandleHttpResponses
 	 *
 	 * @return boolean "true" if header exists
 	 */
-	public function inHeader(string $field);
+	public function inHeader(string $field): bool;
 
 	/**
 	 * Returns the headers as an associated array
@@ -78,47 +78,47 @@ interface ICanHandleHttpResponses
 	 *
 	 * @return string[][] associated header array
 	 */
-	public function getHeaderArray();
+	public function getHeaderArray(): array;
 
 	/**
 	 * @return bool
 	 */
-	public function isSuccess();
+	public function isSuccess(): bool;
 
 	/**
 	 * @return string
 	 */
-	public function getUrl();
+	public function getUrl(): string;
 
 	/**
 	 * @return string
 	 */
-	public function getRedirectUrl();
+	public function getRedirectUrl(): string;
 
 	/**
 	 * @see MessageInterface::getBody()
 	 *
 	 * @return string
 	 */
-	public function getBody();
+	public function getBody(): string;
 
 	/**
 	 * @return boolean
 	 */
-	public function isRedirectUrl();
+	public function isRedirectUrl(): bool;
 
 	/**
 	 * @return integer
 	 */
-	public function getErrorNumber();
+	public function getErrorNumber(): int;
 
 	/**
 	 * @return string
 	 */
-	public function getError();
+	public function getError(): string;
 
 	/**
 	 * @return boolean
 	 */
-	public function isTimeout();
+	public function isTimeout(): bool;
 }
diff --git a/src/Object/Post.php b/src/Object/Post.php
index fec3b3f2b3..4c5aa8a21b 100644
--- a/src/Object/Post.php
+++ b/src/Object/Post.php
@@ -1008,7 +1008,7 @@ class Post
 	/**
 	 * @return string
 	 */
-	private function getRedirectUrl()
+	private function getRedirectUrl(): string
 	{
 		return $this->redirect_url;
 	}
diff --git a/src/Object/Search/ContactResult.php b/src/Object/Search/ContactResult.php
index dabae1f4d3..8895f0ce0b 100644
--- a/src/Object/Search/ContactResult.php
+++ b/src/Object/Search/ContactResult.php
@@ -110,7 +110,7 @@ class ContactResult implements IResult
 	/**
 	 * @return string
 	 */
-	public function getUrl()
+	public function getUrl(): string
 	{
 		return $this->url;
 	}
diff --git a/src/Util/EMailer/MailBuilder.php b/src/Util/EMailer/MailBuilder.php
index 6e892cf254..e6b745b979 100644
--- a/src/Util/EMailer/MailBuilder.php
+++ b/src/Util/EMailer/MailBuilder.php
@@ -164,7 +164,7 @@ abstract class MailBuilder
 	 *
 	 * @return string[][]
 	 */
-	public function getHeaders()
+	public function getHeaders(): array
 	{
 		return $this->headers;
 	}
@@ -182,7 +182,7 @@ abstract class MailBuilder
 	 * @param string[][] $headers
 	 * @return $this
 	 */
-	public function withHeaders(array $headers)
+	public function withHeaders(array $headers): MailBuilder
 	{
 		$this->headers = $headers;
 
diff --git a/src/Util/Mimetype.php b/src/Util/Mimetype.php
index d7a702d71c..ca57648771 100644
--- a/src/Util/Mimetype.php
+++ b/src/Util/Mimetype.php
@@ -29,7 +29,7 @@ class Mimetype
 	 * @param string $filename filename
 	 * @return mixed array or string
 	 */
-	public static function getContentType($filename)
+	public static function getContentType(string $filename)
 	{
 		$mime_types = [
 	
diff --git a/src/Util/ParseUrl.php b/src/Util/ParseUrl.php
index abd9154da1..f4c78df8a5 100644
--- a/src/Util/ParseUrl.php
+++ b/src/Util/ParseUrl.php
@@ -59,7 +59,7 @@ class ParseUrl
 	 * @param string $accept content-type to accept
 	 * @return array content type
 	 */
-	public static function getContentType(string $url, string $accept = HttpClientAccept::DEFAULT)
+	public static function getContentType(string $url, string $accept = HttpClientAccept::DEFAULT): array
 	{
 		$curlResult = DI::httpClient()->head($url, [HttpClientOptions::ACCEPT_CONTENT => $accept]);