diff --git a/src/clib/pioc_support.c b/src/clib/pioc_support.c
index d57459de104..849652e6a6a 100644
--- a/src/clib/pioc_support.c
+++ b/src/clib/pioc_support.c
@@ -2433,7 +2433,11 @@ inq_file_metadata(file_desc_t *file, int ncid, int iotype, int *nvars,
 }
 
 /**
- * Find the appropriate IOTYPE from mode flags to nc_open().
+ * Find the appropriate IOTYPE from mode flags to nc_open(). The
+ * following flags have meaning:
+ * - NC_NETCDF4 - use netCDF-4/HDF5 format
+ * - NC_MPIIO - when used with NC_NETCDF4, use parallel I/O.
+ * - NC_PNETCDF - use classic format with pnetcdf parallel I/O.
  *
  * @param mode the mode flag from nc_open().
  * @param iotype pointer that gets the IOTYPE.
diff --git a/tests/ncint/tst_ncint_perf.c b/tests/ncint/tst_ncint_perf.c
index 8e6a6b35dd7..820dc463558 100644
--- a/tests/ncint/tst_ncint_perf.c
+++ b/tests/ncint/tst_ncint_perf.c
@@ -24,7 +24,7 @@
 #define NDIM2 2
 #define NDIM3 3
 #define NUM_TIMESTEPS 1
-#define NUM_MODES 2
+#define NUM_MODES 4
 
 extern NC_Dispatch NCINT_dispatcher;
 
@@ -95,9 +95,13 @@ main(int argc, char **argv)
             float num_megabytes = DIM_LEN_X * DIM_LEN_Y * sizeof(int) / (float)1000000 * NUM_TIMESTEPS;
             float delta_in_sec;
             float mb_per_sec;
-            int cmode[NUM_MODES] = {NC_PIO, NC_PIO|NC_NETCDF4};
-            char mode_name[NUM_MODES][NC_MAX_NAME + 1] = {"netCDF-classic sequential",
-                                                          "netCDF-4/HDF5 sequential"};
+            int cmode[NUM_MODES] = {NC_PIO, NC_PIO|NC_NETCDF4,
+                                    NC_PIO|NC_NETCDF4|NC_MPIIO,
+                                    NC_PIO|NC_PNETCDF};
+            char mode_name[NUM_MODES][NC_MAX_NAME + 1] = {"classic sequential",
+                                                          "netCDF-4 sequential",
+                                                          "netCDF-4 parallel I/O",
+                                                          "classic pnetcdf parallel I/O"};
             int t, m;
 
             for (m = 0; m < NUM_MODES; m++)