diff --git a/hysop/backend/device/opencl/opencl_array_backend.py b/hysop/backend/device/opencl/opencl_array_backend.py
index 2ea4948d89fb108c01e133ec8252e8353a67f987..d6df937593b0a358bddefb73a6bdeb7b4b8bfdc7 100644
--- a/hysop/backend/device/opencl/opencl_array_backend.py
+++ b/hysop/backend/device/opencl/opencl_array_backend.py
@@ -1500,19 +1500,19 @@ class OpenClArrayBackend(ArrayBackend):
             dtype = np.float32
             msg = 'OpenClArrayBackend promoted float16 to float32 in array allocation of shape {}.'
             msg = msg.format(shape)
-            # warnings.warn(RuntimeWarning(msg))
+            warnings.warn(RuntimeWarning(msg))
         # FIXME OpenCL long double support
         if dtype == np.longdouble:
             msg = 'OpenClArrayBackend demoted {} to float64 in array allocation of shape {}.'
             msg = msg.format(dtype, shape)
             dtype = np.float64
-            # warnings.warn(RuntimeWarning(msg))
+            warnings.warn(RuntimeWarning(msg))
         # FIXME OpenCL bool support
         if dtype == np.bool_:
             dtype = HYSOP_BOOL
             msg = 'OpenClArrayBackend promoted np.bool_ to {} in array allocation of shape {}.'
             msg = msg.format(dtype, shape)
-            # warnings.warn(RuntimeWarning(msg))
+            warnings.warn(RuntimeWarning(msg))
 
         shape = to_tuple(shape)