diff --git a/snappymail/v/0.0.0/app/libraries/snappymail/gpg/base.php b/snappymail/v/0.0.0/app/libraries/snappymail/gpg/base.php
index 3a6be33f2..74c474a7d 100644
--- a/snappymail/v/0.0.0/app/libraries/snappymail/gpg/base.php
+++ b/snappymail/v/0.0.0/app/libraries/snappymail/gpg/base.php
@@ -483,7 +483,7 @@ abstract class Base
 
 	protected static function findBinary($name) : ?string
 	{
-		$binary = \trim((string) `which $name`);
+		$binary = \function_exists('shell_exec') ? \trim((string) `which $name`) : '';
 		if ($binary && \RainLoop\Utils::inOpenBasedir($binary) && \is_executable($binary)) {
 			return $binary;
 		}