diff --git a/src/parallel_io.c b/src/parallel_io.c
index f48aaa04e59cb084f6d1a4af0a904a7476b470ac..6320709f3595c4e03237e36a03a5e55fa4f52969 100644
--- a/src/parallel_io.c
+++ b/src/parallel_io.c
@@ -270,7 +270,7 @@ void read_ic_parallel(char* fileName, double dim[3], struct part** parts,
             COMPULSORY);
   readArray(h_grp, "SmoothingLength", FLOAT, *N, 1, *parts, N_total, offset, h,
             COMPULSORY);
-  readArray(h_grp, "InternalEnergy", FLOAT, *N, 1, *parts, N_total, offset, u,
+  readArray(h_grp, "InternalEnergy", FLOAT, *N, 1, *parts, N_total, offset, entropy,
             COMPULSORY);
   readArray(h_grp, "ParticleIDs", ULONGLONG, *N, 1, *parts, N_total, offset, id,
             COMPULSORY);
@@ -580,7 +580,7 @@ void write_output_parallel(struct engine* e, struct UnitSystem* us,
   writeArray(h_grp, fileName, xmfFile, "SmoothingLength", FLOAT, N, 1, parts,
              N_total, mpi_rank, offset, h, us, UNIT_CONV_LENGTH);
   writeArray(h_grp, fileName, xmfFile, "InternalEnergy", FLOAT, N, 1, parts,
-             N_total, mpi_rank, offset, u, us, UNIT_CONV_ENERGY_PER_UNIT_MASS);
+             N_total, mpi_rank, offset, entropy, us, UNIT_CONV_ENERGY_PER_UNIT_MASS);
   writeArray(h_grp, fileName, xmfFile, "ParticleIDs", ULONGLONG, N, 1, parts,
              N_total, mpi_rank, offset, id, us, UNIT_CONV_NO_UNITS);
   /* writeArray(h_grp, fileName, xmfFile, "TimeStep", FLOAT, N, 1, parts,
diff --git a/src/serial_io.c b/src/serial_io.c
index 0db21c0f84f799c38075f2edc94ad697571c9180..a8b9ecfdde135f0933b6942e0efb125867510908 100644
--- a/src/serial_io.c
+++ b/src/serial_io.c
@@ -311,7 +311,7 @@ void read_ic_serial(char* fileName, double dim[3], struct part** parts, int* N,
       readArray(h_grp, "SmoothingLength", FLOAT, *N, 1, *parts, N_total, offset,
                 h, COMPULSORY);
       readArray(h_grp, "InternalEnergy", FLOAT, *N, 1, *parts, N_total, offset,
-                u, COMPULSORY);
+                entropy, COMPULSORY);
       readArray(h_grp, "ParticleIDs", ULONGLONG, *N, 1, *parts, N_total, offset,
                 id, COMPULSORY);
       /* readArray(h_grp, "TimeStep", FLOAT, *N, 1, *parts, N_total, offset, dt,
@@ -670,7 +670,7 @@ void write_output_serial(struct engine* e, struct UnitSystem* us, int mpi_rank,
       writeArray(h_grp, "SmoothingLength", FLOAT, N, 1, N_total, offset, parts,
                  h);
       writeArray(h_grp, "InternalEnergy", FLOAT, N, 1, N_total, offset, parts,
-                 u);
+                 entropy);
       writeArray(h_grp, "ParticleIDs", ULONGLONG, N, 1, N_total, offset, parts,
                  id);
       //writeArray(h_grp, "TimeStep", FLOAT, N, 1, N_total, offset, parts, dt);