diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 8613fc6fb5..27551566ac 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -1398,9 +1398,13 @@ ParallelWorkerMain(Datum main_arg)
 
 	/*
 	 * Set the client encoding to the database encoding, since that is what
-	 * the leader will expect.
+	 * the leader will expect.  (We're cheating a bit by not calling
+	 * PrepareClientEncoding first.  It's okay because this call will always
+	 * result in installing a no-op conversion.  No error should be possible,
+	 * but check anyway.)
 	 */
-	SetClientEncoding(GetDatabaseEncoding());
+	if (SetClientEncoding(GetDatabaseEncoding()) < 0)
+		elog(ERROR, "SetClientEncoding(%d) failed", GetDatabaseEncoding());
 
 	/*
 	 * Load libraries that were loaded by original backend.  We want to do
diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index f44d942aa4..6ba6d08b24 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -690,6 +690,24 @@ check_client_encoding(char **newval, void **extra, GucSource source)
 	/* Get the canonical name (no aliases, uniform case) */
 	canonical_name = pg_encoding_to_char(encoding);
 
+	/*
+	 * Parallel workers send data to the leader, not the client.  They always
+	 * send data using the database encoding; therefore, we should never
+	 * actually change the client encoding in a parallel worker.  However,
+	 * during parallel worker startup, we want to accept the leader's
+	 * client_encoding setting so that anyone who looks at the value in the
+	 * worker sees the same value that they would see in the leader.  A change
+	 * other than during startup, for example due to a SET clause attached to
+	 * a function definition, should be rejected, as there is nothing we can
+	 * do inside the worker to make it take effect.
+	 */
+	if (IsParallelWorker() && !InitializingParallelWorker)
+	{
+		GUC_check_errcode(ERRCODE_INVALID_TRANSACTION_STATE);
+		GUC_check_errdetail("Cannot change \"client_encoding\" during a parallel operation.");
+		return false;
+	}
+
 	/*
 	 * If we are not within a transaction then PrepareClientEncoding will not
 	 * be able to look up the necessary conversion procs.  If we are still
@@ -700,11 +718,15 @@ check_client_encoding(char **newval, void **extra, GucSource source)
 	 * It seems like a bad idea for client_encoding to change that way anyhow,
 	 * so we don't go out of our way to support it.
 	 *
+	 * In a parallel worker, we might as well skip PrepareClientEncoding since
+	 * we're not going to use its results.
+	 *
 	 * Note: in the postmaster, or any other process that never calls
 	 * InitializeClientEncoding, PrepareClientEncoding will always succeed,
 	 * and so will SetClientEncoding; but they won't do anything, which is OK.
 	 */
-	if (PrepareClientEncoding(encoding) < 0)
+	if (!IsParallelWorker() &&
+		PrepareClientEncoding(encoding) < 0)
 	{
 		if (IsTransactionState())
 		{
@@ -758,28 +780,11 @@ assign_client_encoding(const char *newval, void *extra)
 	int			encoding = *((int *) extra);
 
 	/*
-	 * Parallel workers send data to the leader, not the client.  They always
-	 * send data using the database encoding.
+	 * In a parallel worker, we never override the client encoding that was
+	 * set by ParallelWorkerMain().
 	 */
 	if (IsParallelWorker())
-	{
-		/*
-		 * During parallel worker startup, we want to accept the leader's
-		 * client_encoding setting so that anyone who looks at the value in
-		 * the worker sees the same value that they would see in the leader.
-		 */
-		if (InitializingParallelWorker)
-			return;
-
-		/*
-		 * A change other than during startup, for example due to a SET clause
-		 * attached to a function definition, should be rejected, as there is
-		 * nothing we can do inside the worker to make it take effect.
-		 */
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
-				 errmsg("cannot change \"client_encoding\" during a parallel operation")));
-	}
+		return;
 
 	/* We do not expect an error if PrepareClientEncoding succeeded */
 	if (SetClientEncoding(encoding) < 0)