diff --git a/CMakeLists.txt b/CMakeLists.txt
index fb90ea213..8a592dba0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -35,8 +35,9 @@ SET(netCDF_LIB_VERSION 18)
 SET(netCDF_SO_VERSION 18)
 SET(PACKAGE_VERSION ${VERSION})
 
-# Version of the dispatch table, in case we change it.
-SET(NC_DISPATCH_VERSION 1)
+# Version of the dispatch table. This must match the value in
+# configure.ac.
+SET(NC_DISPATCH_VERSION 2)
 
 # Get system configuration, Use it to determine osname, os release, cpu. These
 # will be used when committing to CDash.
diff --git a/configure.ac b/configure.ac
index e240bd96a..b298269ce 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1620,6 +1620,12 @@ AX_SET_META([NC_HAS_PAR_FILTERS], [$hdf5_supports_par_filters],[yes])
 AX_SET_META([NC_HAS_BYTERANGE],[$enable_byterange],[yes])
 AX_SET_META([NC_HAS_NCZARR],[$enable_nczarr],[yes])
 AX_SET_META([NC_HAS_NCZARR_S3],[$enable_s3_sdk],[yes])
+
+# This is the version of the dispatch table. If the dispatch table is
+# changed, this should be incremented, so that user-defined format
+# applications like PIO can determine whether they have an appropriate
+# dispatch table to submit. If this is changed, make sure the value in
+# CMakeLists.txt also changes to match.
 AC_SUBST([NC_DISPATCH_VERSION], [2])
 
 #####