diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7227f87edc6..11cdcf8a540 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -252,6 +252,11 @@ else()
   find_package (PnetCDF COMPONENTS C)
 endif()
 
+# Did we find pnetCDF? If so, set _PNETCDF in config.h.
+if (PnetCDF_C_FOUND)
+  set(_PNETCDF 1)
+endif ()
+
 #==============================================================================
 #  INCLUDE SOURCE DIRECTORIES
 #==============================================================================
@@ -311,6 +316,8 @@ CHECK_C_SOURCE_COMPILES("
       choke me
 #endif
 int main() {return 0;}" HAVE_NETCDF_PAR)
+
+# Set this synonym for HAVE_NETCDF_PAR. It is defined in config.h.
 if (HAVE_NETCDF_PAR)
   set(_NETCDF4 1)
 endif ()
diff --git a/cmake_config.h.in b/cmake_config.h.in
index 399e1fe81d6..7561db067df 100644
--- a/cmake_config.h.in
+++ b/cmake_config.h.in
@@ -36,7 +36,8 @@
 /* Does netCDF support parallel I/O for netCDF/HDF5 files? */
 #cmakedefine HAVE_NETCDF_PAR
 
-/* Does PIO support netCDF/HDF5 files? */
+/* Does PIO support netCDF/HDF5 files? (Will be same as
+ * HAVE_NETCDF_PAR). */
 #cmakedefine _NETCDF4
 
 /* Does netCDF and HDF5 support parallel I/O filters? */
diff --git a/src/clib/CMakeLists.txt b/src/clib/CMakeLists.txt
index d8dc3f63a00..35b4d8c5bb4 100644
--- a/src/clib/CMakeLists.txt
+++ b/src/clib/CMakeLists.txt
@@ -118,8 +118,8 @@ endif ()
 if (PnetCDF_C_FOUND)
   target_include_directories (pioc
     PUBLIC ${PnetCDF_C_INCLUDE_DIRS})
-  target_compile_definitions (pioc
-    PUBLIC _PNETCDF)
+  # target_compile_definitions (pioc
+  #   PUBLIC _PNETCDF)
   target_link_libraries (pioc
     PUBLIC ${PnetCDF_C_LIBRARIES})
 
diff --git a/src/flib/CMakeLists.txt b/src/flib/CMakeLists.txt
index d2b535abda4..0c7333aea19 100644
--- a/src/flib/CMakeLists.txt
+++ b/src/flib/CMakeLists.txt
@@ -233,8 +233,8 @@ endif ()
 if (PnetCDF_Fortran_FOUND)
   target_include_directories (piof
     PUBLIC ${PnetCDF_Fortran_INCLUDE_DIRS})
-  target_compile_definitions (piof
-    PUBLIC _PNETCDF)
+  # target_compile_definitions (piof
+  #   PUBLIC _PNETCDF)
   target_link_libraries (piof
     PUBLIC ${PnetCDF_Fortran_LIBRARIES})