diff --git a/GPUSimulators/FORCE.py b/GPUSimulators/FORCE.py
index 205c4d7..092711a 100644
--- a/GPUSimulators/FORCE.py
+++ b/GPUSimulators/FORCE.py
@@ -24,7 +24,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 from GPUSimulators import Simulator, Common
 from GPUSimulators.Simulator import BaseSimulator, BoundaryCondition
 import numpy as np
-
+import ctypes
 #from pycuda import gpuarray
 from hip import hip,hiprtc