diff --git a/satpy/readers/seviri_base.py b/satpy/readers/seviri_base.py
index aa224b0d6a..c9ad563899 100644
--- a/satpy/readers/seviri_base.py
+++ b/satpy/readers/seviri_base.py
@@ -700,7 +700,7 @@ def calibrate(self, data, calibration):
                              "brightness_temperature"]:
             gain, offset = self.get_gain_offset()
             res = self._algo.convert_to_radiance(
-                data.astype(np.float32), gain, offset
+                data.astype(np.float32), np.float32(gain), np.float32(offset)
             )
         else:
             raise ValueError(
diff --git a/satpy/tests/reader_tests/test_seviri_l1b_native.py b/satpy/tests/reader_tests/test_seviri_l1b_native.py
index e7a5d0f5f3..5c6a86596e 100644
--- a/satpy/tests/reader_tests/test_seviri_l1b_native.py
+++ b/satpy/tests/reader_tests/test_seviri_l1b_native.py
@@ -1314,6 +1314,8 @@ def test_read_physical_seviri_nat_file(full_path):
     with warnings.catch_warnings():
         warnings.filterwarnings("ignore", category=UserWarning)
         scene.load(["VIS006"])
+        assert scene["VIS006"].dtype == np.float32
+        assert scene["VIS006"].values.dtype == np.float32
         assert scene["VIS006"].shape == (3712, 3712)
         assert isinstance(scene["VIS006"], xr.core.dataarray.DataArray)