diff --git a/inc/TRestAxionTrueWolterOptics.h b/inc/TRestAxionTrueWolterOptics.h
index 3dfc5ea9..5dece507 100644
--- a/inc/TRestAxionTrueWolterOptics.h
+++ b/inc/TRestAxionTrueWolterOptics.h
@@ -54,7 +54,7 @@ class TRestAxionTrueWolterOptics : public TRestAxionOptics {
     std::vector<Double_t> fThickness;  //!
 
     /// Distance between mirror stacks in mm. See schematic figure.
-    /// This is here calculated using the functions from 
+    /// This is here calculated using the functions from
     /// https://backend.orbit.dtu.dk/ws/portalfiles/portal/122353510/phdthesis_for_DTU_orbit.pdf.
     std::vector<Double_t> fXSep;  //!