diff --git a/reader/HDF5MetadataSource.cpp b/reader/HDF5MetadataSource.cpp
index bde7cd52..2109d685 100644
--- a/reader/HDF5MetadataSource.cpp
+++ b/reader/HDF5MetadataSource.cpp
@@ -647,6 +647,12 @@ HDF5MetadataSource::OpenResult HDF5MetadataSource::Open(const std::string &filen
 
         DetectorSetup detector = DetDECTRIS(image_size_x, image_size_y, detector_name, {});
         detector.PixelSize_um(master_file->GetFloat("/entry/instrument/detector/x_pixel_size") * 1e6);
+        // Sensor thickness/material drive the parallax/absorption model, so take them from the file
+        // rather than the DetectorSetup default (NXmx stores thickness in metres).
+        if (master_file->Exists("/entry/instrument/detector/sensor_thickness"))
+            detector.SensorThickness_um(master_file->GetFloat("/entry/instrument/detector/sensor_thickness") * 1e6);
+        if (master_file->Exists("/entry/instrument/detector/sensor_material"))
+            detector.SensorMaterial(master_file->GetString("/entry/instrument/detector/sensor_material"));
         detector.SaturationLimit(master_file->GetInt("/entry/instrument/detector/saturation_value"));
         detector.MinFrameTime(std::chrono::microseconds(0));
         detector.MinCountTime(std::chrono::microseconds(0));