diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 000524d..0c8bc8f 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -923,8 +923,9 @@ PostmasterMain(int argc, char *argv[])
 	process_shared_preload_libraries();
 
 	/*
-	 * Now that loadable modules have had their chance to register background
-	 * workers, calculate MaxBackends.
+	 * Calculate the maximum possible number of backends.  This must happen
+	 * after we have finished initalizing GUCs and before shared memory size
+	 * is determined.
 	 */
 	InitializeMaxBackends();
 
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 7b19714..c99e7c0 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -482,9 +482,8 @@ pg_split_opts(char **argv, int *argcp, const char *optstr)
 /*
  * Initialize MaxBackends value from config options.
  *
- * This must be called after modules have had the chance to register background
- * workers in shared_preload_libraries, and before shared memory size is
- * determined.
+ * This must happen after we finish setting the initial values for GUCs,
+ * and before shared memory size is determined.
  *
  * Note that in EXEC_BACKEND environment, the value is passed down from
  * postmaster to subprocesses via BackendParameters in SubPostmasterMain; only