diff --git a/ChangeLog b/ChangeLog
index b1e9272c0692a43be5c759aa014b62854d57147e..b110284d9f00a8ae94c1396618bd6a761822ee44 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2025-03-27  Uwe Schulzweida
+
+	* vlistChangeZaxis: added call to delete_chunks() (bug fix)
+
+2025-03-14  Uwe Schulzweida
+
+	* enable-hirlam-extensions failed since release 2.5.1 (bug fix)
+
 2025-03-05  Uwe Schulzweida
 
 	* Version 2.5.1 released
diff --git a/configure.ac b/configure.ac
index 112aeb0f2fb9b8d1d95499e41c054f5053d80b1f..a6026ba7cf6f9fa1af8a32d7dcba0566be7a1e5f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7,7 +7,7 @@
 AC_PREREQ([2.69])
 LT_PREREQ([2.4.6])
 
-AC_INIT([cdi],[2.5.1.1],[https://mpimet.mpg.de/cdi])
+AC_INIT([cdi],[2.5.2],[https://mpimet.mpg.de/cdi])
 AC_DEFINE_UNQUOTED(CDI, ["$PACKAGE_VERSION"], [CDI version])
 
 AC_CONFIG_AUX_DIR([config])
diff --git a/src/cdf_filter.c b/src/cdf_filter.c
index 615208ca3c0e2bce59972f73e112abb3b27a3978..91773ffe7267868fa9cc658611f1d405d2fad511 100644
--- a/src/cdf_filter.c
+++ b/src/cdf_filter.c
@@ -94,8 +94,7 @@ cdf_def_var_filter(int ncid, int ncvarID, const char *filterSpec)
           for (size_t i = 0; i < nfilters; i++)
             {
               unsigned int filterid = filters[i]->filterid;
-              // printf("filter %zu id:%d nparams:%zu param1 %d %d\n", i + 1, filterid, filters[i]->nparams, filters[i]->params[0],
-              // filters[i]->params[1]);
+              // printf("filter %zu id:%d nparams:%zu param1 %d\n", i + 1, filterid, filters[i]->nparams, filters[i]->params[0]);
               status = nc_def_var_filter(ncid, ncvarID, filterid, filters[i]->nparams, filters[i]->params);
               if (status != NC_NOERR)
                 {
diff --git a/src/grb_write.c b/src/grb_write.c
index 217904313fda17b3dfc7d6f1a7d3caf7ed14f976..7f699aac75d87694f237e30127a9845a49aa8727 100644
--- a/src/grb_write.c
+++ b/src/grb_write.c
@@ -316,8 +316,8 @@ grbCopyField(stream_t *streamptr2, stream_t *streamptr1)
           size_t numMissVals = 0;
 
           int vlistID = streamptr1->vlistID;
-          int varID = record->varID;
-          int levelID = record->levelID;
+          int varID = recinfo->varID;
+          int levelID = recinfo->levelID;
           int gridID = vlistInqVarGrid(vlistID, varID);
 
           size_t gridsize = gridInqSize(gridID);
diff --git a/src/vlist.c b/src/vlist.c
index a6bf4888ee0e7ebcea82061e0bcf35a52c14eb74..998026b61d9e8383fe6d6c45cf24a0f22a2fa7e3 100644
--- a/src/vlist.c
+++ b/src/vlist.c
@@ -507,6 +507,22 @@ vlist_generate_zaxis(int vlistID, int zaxistype, int nlevels, const double *leve
   return zaxisID;
 }
 
+static void
+delete_chunks(int vlistID, int varID)
+{
+  int chunkKeys[4] = { CDI_KEY_CHUNKSIZE_DIMX, CDI_KEY_CHUNKSIZE_DIMY, CDI_KEY_CHUNKSIZE_DIMZ, CDI_KEY_CHUNKSIZE_DIMT };
+  for (int i = 0; i < 4; ++i)
+    {
+      int chunkSize = 0;
+      cdiInqKeyInt(vlistID, varID, chunkKeys[i], &chunkSize);
+      if (chunkSize != 0) cdiDeleteKey(vlistID, varID, chunkKeys[i]);
+    }
+
+  int chunkSize = 0;
+  cdiInqKeyInt(vlistID, varID, CDI_KEY_CHUNKSIZE, &chunkSize);
+  if (chunkSize > 0) cdiDeleteKey(vlistID, varID, CDI_KEY_CHUNKSIZE);
+}
+
 /*
 @Function  vlistCopyFlag
 @Title     Copy some entries of a variable list
@@ -708,6 +724,7 @@ vlistCopyFlag(int vlistID2, int vlistID1)
 
                 zaxisID = zaxisID2;
                 vars2[varID2].zaxisID = zaxisID2;
+                delete_chunks(vlistID2, varID2);
               }
 
             for (int levID = 0; levID < nlevs2; levID++)
@@ -1350,22 +1367,6 @@ vlistGridIndex(int vlistID, int gridID)
   return index;
 }
 
-static void
-delete_chunks(int vlistID, int varID)
-{
-  int chunkKeys[4] = { CDI_KEY_CHUNKSIZE_DIMX, CDI_KEY_CHUNKSIZE_DIMY, CDI_KEY_CHUNKSIZE_DIMZ, CDI_KEY_CHUNKSIZE_DIMT };
-  for (int i = 0; i < 4; ++i)
-    {
-      int chunkSize = 0;
-      cdiInqKeyInt(vlistID, varID, chunkKeys[i], &chunkSize);
-      if (chunkSize != 0) cdiDeleteKey(vlistID, varID, chunkKeys[i]);
-    }
-
-  int chunkSize = 0;
-  cdiInqKeyInt(vlistID, varID, CDI_KEY_CHUNKSIZE, &chunkSize);
-  if (chunkSize > 0) cdiDeleteKey(vlistID, varID, CDI_KEY_CHUNKSIZE);
-}
-
 void
 vlistChangeGridIndex(int vlistID, int index, int gridID)
 {
@@ -1457,6 +1458,7 @@ vlistChangeZaxisIndex(int vlistID, int index, int zaxisID)
         if (vlistptr->vars[varID].zaxisID == zaxisIDold)
           {
             vlistptr->vars[varID].zaxisID = zaxisID;
+            delete_chunks(vlistID, varID);
             if (vlistptr->vars[varID].levinfo && nlevs != nlevsOld)
               {
                 vlistptr->vars[varID].levinfo
@@ -1490,6 +1492,7 @@ vlistChangeZaxis(int vlistID, int zaxisID1, int zaxisID2)
     if (vlistptr->vars[varID].zaxisID == zaxisID1)
       {
         vlistptr->vars[varID].zaxisID = zaxisID2;
+        delete_chunks(vlistID, varID);
 
         if (vlistptr->vars[varID].levinfo && nlevs2 != nlevs1)
           {