diff --git a/.github/workflows/withspack.yml b/.github/workflows/withspack.yml
index 998d61ea0..21e373cdc 100644
--- a/.github/workflows/withspack.yml
+++ b/.github/workflows/withspack.yml
@@ -59,8 +59,8 @@ jobs:
         # the || true prevents a fail if parallelio is not installed
         #        spack uninstall -y parallelio@=develop+pnetcdf+fortran ^mpich || true
         #        spack dev-build -d $GITHUB_WORKSPACE parallelio@=develop+pnetcdf+fortran ^mpich
-        spack uninstall -y parallelio@=develop+pnetcdf+fortran ^mpich || true
-        spack dev-build -d $GITHUB_WORKSPACE parallelio@=develop+pnetcdf+fortran ^mpich
+        spack uninstall -y parallelio@develop+pnetcdf+fortran ^mpich || true
+        spack dev-build -d $GITHUB_WORKSPACE parallelio@develop+pnetcdf+fortran ^mpich
 
     - name: Test parallelio
       run: |
@@ -72,6 +72,6 @@ jobs:
         popd
 
 
-    - name: Setup tmate session
-      if: ${{ failure() }}
-      uses: mxschmitt/action-tmate@v3
+#    - name: Setup tmate session
+#      if: ${{ failure() }}
+#      uses: mxschmitt/action-tmate@v3
diff --git a/src/clib/pio.h b/src/clib/pio.h
index a4b20b752..b15d61b0b 100644
--- a/src/clib/pio.h
+++ b/src/clib/pio.h
@@ -27,6 +27,9 @@
     (((NC_VERSION_MAJOR == Maj) && (NC_VERSION_MINOR == Min) && (NC_VERSION_PATCH >= Pat)) || \
      ((NC_VERSION_MAJOR == Maj) && (NC_VERSION_MINOR > Min)) || (NC_VERSION_MAJOR > Maj))
 
+#ifndef NC_FillValue
+#define NC_FillValue _FillValue
+#endif
 
 /** PIO_OFFSET is an integer type of size sufficient to represent the
  * size (in bytes) of the largest file supported by MPI. This is not
diff --git a/src/clib/pio_nc.c b/src/clib/pio_nc.c
index 2808e45ec..d6849b59a 100644
--- a/src/clib/pio_nc.c
+++ b/src/clib/pio_nc.c
@@ -2322,7 +2322,7 @@ PIOc_def_var(int ncid, const char *name, nc_type xtype, int ndims,
  *
  * When the fill mode for the file is NC_FILL, then fill values are
  * used for missing data. This function sets the fill value to be used
- * for a variable. If no specific fill value is set (as a _FillValue
+ * for a variable. If no specific fill value is set (as a NC_FillValue
  * attribute), then the default fill values from netcdf.h are used.
  *
  * NetCDF-4 and pnetcdf files allow setting fill_mode (to NC_FILL or
@@ -2430,7 +2430,7 @@ PIOc_def_var_fill(int ncid, int varid, int fill_mode, const void *fill_valuep)
             {
                 ierr = nc_set_fill(file->fh, NC_FILL, NULL);
                 if (!ierr)
-                    ierr = nc_put_att(file->fh, varid, _FillValue, xtype, 1, fill_valuep);
+                    ierr = nc_put_att(file->fh, varid, NC_FillValue, xtype, 1, fill_valuep);
             }
         }
         else
@@ -2477,7 +2477,7 @@ PIOc_inq_var_fill(int ncid, int varid, int *no_fill, void *fill_valuep)
 {
     iosystem_desc_t *ios;  /* Pointer to io system information. */
     file_desc_t *file;     /* Pointer to file information. */
-    nc_type xtype;         /* Type of variable and its _FillValue attribute. */
+    nc_type xtype;         /* Type of variable and its NC_FillValue attribute. */
     PIO_Offset type_size;  /* Size in bytes of this variable's type. */
     int mpierr = MPI_SUCCESS, mpierr2;  /* Return code from MPI function codes. */
     int ierr = PIO_NOERR;  /* Return code from function calls. */
@@ -2574,7 +2574,7 @@ PIOc_inq_var_fill(int ncid, int varid, int *no_fill, void *fill_valuep)
 
             if (!ierr && fill_valuep)
             {
-                ierr = nc_get_att(file->fh, varid, _FillValue, fill_valuep);
+                ierr = nc_get_att(file->fh, varid, NC_FillValue, fill_valuep);
                 if (ierr == NC_ENOTATT)
                 {
                     char char_fill_value = NC_FILL_CHAR;