diff --git a/src/hydro/Gadget2/hydro_part.h b/src/hydro/Gadget2/hydro_part.h
index 2d9c0fdbffadc5f374136f853f959425bd480747..e0c29c8e420aafbc9b797883663c9d50d21200b0 100644
--- a/src/hydro/Gadget2/hydro_part.h
+++ b/src/hydro/Gadget2/hydro_part.h
@@ -181,6 +181,9 @@ struct part {
   /*! Time-step length */
   timebin_t time_bin;
 
+  /*! Tree-depth at which size / 2 <= h * gamma < size */
+  char depth_h;
+
   /*! Time-step limiter information */
   struct timestep_limiter_data limiter_data;
 
diff --git a/src/hydro/Minimal/hydro_part.h b/src/hydro/Minimal/hydro_part.h
index 30a7cbb19a71ca9b9f6d21bd5ba68f451b07c25a..f05775c5d4bac79e7d51dab4db0b758498466e78 100644
--- a/src/hydro/Minimal/hydro_part.h
+++ b/src/hydro/Minimal/hydro_part.h
@@ -199,6 +199,9 @@ struct part {
   /*! Time-step length */
   timebin_t time_bin;
 
+  /*! Tree-depth at which size / 2 <= h * gamma < size */
+  char depth_h;
+
   /*! Time-step limiter information */
   struct timestep_limiter_data limiter_data;
 
diff --git a/src/stars/Basic/stars_part.h b/src/stars/Basic/stars_part.h
index b023d8205a5694bcc641211f088d5d7ae867a5a1..903f6c075146864ce506479e645ae7efae4d3d5d 100644
--- a/src/stars/Basic/stars_part.h
+++ b/src/stars/Basic/stars_part.h
@@ -81,6 +81,9 @@ struct spart {
   /*! Particle time bin */
   timebin_t time_bin;
 
+  /*! Tree-depth at which size / 2 <= h * gamma < size */
+  char depth_h;
+
   /*! Star formation struct */
   struct star_formation_spart_data sf_data;
 
diff --git a/src/stars/GEAR/stars_part.h b/src/stars/GEAR/stars_part.h
index cbca5a11c158c095738aaf3696cec197ec297c4a..7fa25fcc0563464c38a3d3f4b9e2d3d66e13de7d 100644
--- a/src/stars/GEAR/stars_part.h
+++ b/src/stars/GEAR/stars_part.h
@@ -107,6 +107,9 @@ struct spart {
   /*! Particle time bin */
   timebin_t time_bin;
 
+  /*! Tree-depth at which size / 2 <= h * gamma < size */
+  char depth_h;
+
 #ifdef SWIFT_DEBUG_CHECKS
 
   /* Time of the last drift */
diff --git a/src/stars/None/stars_part.h b/src/stars/None/stars_part.h
index cdc16ec57c5f384eff2f162114fb6cbf83547d9c..116311182001e19d6f9c6a88b0cbf89757cfb4e0 100644
--- a/src/stars/None/stars_part.h
+++ b/src/stars/None/stars_part.h
@@ -58,6 +58,9 @@ struct spart {
   /*! Particle time bin */
   timebin_t time_bin;
 
+  /*! Tree-depth at which size / 2 <= h * gamma < size */
+  char depth_h;
+
   /*! Splitting structure */
   struct particle_splitting_data split_data;