diff --git a/tests/pkg_c25519/tests/01-run.py b/tests/pkg_c25519/tests/01-run.py
index 03f41f2d9a..5d4ec6a847 100755
--- a/tests/pkg_c25519/tests/01-run.py
+++ b/tests/pkg_c25519/tests/01-run.py
@@ -17,7 +17,8 @@ from testrunner import TIMEOUT as DEFAULT_TIMEOUT
 BOARD = os.environ['BOARD']
 # Increase timeout on "real" hardware
 # 170 seconds on `arduino-mega2560`
-TIMEOUT = 200 if BOARD != 'native' else DEFAULT_TIMEOUT
+# ~300 seconds on `z1`
+TIMEOUT = 320 if BOARD != 'native' else DEFAULT_TIMEOUT
 
 
 if __name__ == "__main__":