diff --git a/src/H5Block.c b/src/H5Block.c
index e52eb97..f484031 100644
--- a/src/H5Block.c
+++ b/src/H5Block.c
@@ -724,6 +724,11 @@ _release_hyperslab (
   Define the field layout given the dense index space at the actual
   time step.
 
+  This routine uses an MPI_Allgather, so at large concurrency it should
+  be called as infrequently as possible. For instance, if several timesteps
+  use the same field dimensions, set the layout only once before the
+  first timestep.
+
   \return \c H5PART_SUCCESS on success<br>
   \c H5PART_ERR_MPI<br>
   \c H5PART_ERR_HDF5
diff --git a/test/testframe.c b/test/testframe.c
index 8d83a5c..d4fb73b 100644
--- a/test/testframe.c
+++ b/test/testframe.c
@@ -31,6 +31,7 @@
 #include <string.h>
 #include <H5Part.h>
 #include "testframe.h"
+#include "../src/H5PartPrivate.h"
 
 /*
  * Definitions for the testing structure.
@@ -652,6 +653,7 @@ test_is_valid(H5PartFile *file)
 void
 test_open_objects(H5PartFile *file, int max_objects)
 {
+#ifndef H5_USE_16_API
 	ssize_t nopen = H5Fget_obj_count(file->file, H5F_OBJ_ALL);
 	if (nopen > max_objects)
 	{
@@ -682,5 +684,6 @@ test_open_objects(H5PartFile *file, int max_objects)
 		}
 		free(list);
 	}
+#endif
 }
 
diff --git a/test/write.c b/test/write.c
index 6eea189..e596459 100644
--- a/test/write.c
+++ b/test/write.c
@@ -198,7 +198,7 @@ static void
 test_write_data32(H5PartFile *file, int nparticles, int step)
 {
 	int i,t;
-	h5part_int32_t status;
+	h5part_int32_t status, val;
 	int rank, nprocs;
 
 	float *x,*y,*z;
@@ -244,8 +244,11 @@ test_write_data32(H5PartFile *file, int nparticles, int step)
 			id[i] = i + nparticles*t;
 		}
 
-		status = H5PartSetStep(file, t);
-		RETURN(status, H5PART_SUCCESS, "H5PartSetStep");
+		val = H5PartHasStep(file, t);
+		if (val == 0) {
+			status = H5PartSetStep(file, t);
+			RETURN(status, H5PART_SUCCESS, "H5PartSetStep");
+		}
 
 		/* test a two-part write using views */
 		status = H5PartSetView(file,