diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 5737f62d2da..4e256a3b932 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -2971,6 +2971,9 @@ exec_command_setenv(PsqlScanState scan_state, bool active_branch,
 			/* Set variable to the value of the next argument */
 			setenv(envvar, envval, 1);
 			success = true;
+			/* Hack: track whether we ever set OUTPUT_CHARSET */
+			if (strcmp(envvar, "OUTPUT_CHARSET") == 0)
+				pset.output_charset = true;
 		}
 		free(envvar);
 		free(envval);
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 788555b9782..9b3ae1ed238 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -28,6 +28,7 @@
 #include "fe_utils/mbprint.h"
 #include "fe_utils/string_utils.h"
 #include "mainloop.h"
+#include "mb/pg_wchar.h"
 #include "portability/instr_time.h"
 #include "settings.h"
 
@@ -2630,9 +2631,37 @@ command_no_begin(const char *query)
 void
 addQueryComment(PQExpBuffer buf, const char *label)
 {
-#if defined(ENABLE_NLS)
-	/* This will become conditional once we've settled on the tests to use */
-	label = _(label);
+	/*
+	 * We must not translate the label unless we know that it is representable
+	 * in the server's encoding; for now, restrict ourselves to the case where
+	 * server_encoding == client_encoding.  Even then there's a hazard that
+	 * gettext might produce some other encoding.  Normally gettext emits the
+	 * encoding of LC_CTYPE, but OUTPUT_CHARSET can override that.  gettext
+	 * may keep using the OUTPUT_CHARSET it saw first, so give up if that was
+	 * set on startup or has been set anytime since then.  On Windows the
+	 * encoding gettext uses is not certain to match what we would compute, so
+	 * don't try at all there.
+	 */
+#if defined(ENABLE_NLS) && !defined(WIN32)
+	const char *server_enc = PQparameterStatus(pset.db, "server_encoding");
+	int			client_enc = PQclientEncoding(pset.db);
+
+	if (!pset.output_charset &&
+		server_enc != NULL &&
+		pg_char_to_encoding(server_enc) == client_enc &&
+		pg_get_encoding_from_locale(NULL, false) == client_enc)
+	{
+		const char *translated = _(label);
+		int			len = strlen(translated);
+
+		/*
+		 * In case the checks above miss something, make sure the server
+		 * accepts the bytes.  With equal client and server encodings, this is
+		 * the check the server does.
+		 */
+		if (pg_encoding_verifymbstr(client_enc, translated, len) == len)
+			label = translated;
+	}
 #endif
 
 	printfPQExpBuffer(buf, "/* %s */\n", label);
diff --git a/src/bin/psql/settings.h b/src/bin/psql/settings.h
index a3d088d80cd..80fa45a166a 100644
--- a/src/bin/psql/settings.h
+++ b/src/bin/psql/settings.h
@@ -134,6 +134,7 @@ typedef struct _psqlSettings
 
 	bool		notty;			/* stdin or stdout is not a tty (as determined
 								 * on startup) */
+	bool		output_charset; /* OUTPUT_CHARSET has ever been set */
 	enum trivalue getPassword;	/* prompt the user for a username and password */
 	FILE	   *cur_cmd_source; /* describe the status of the current main
 								 * loop */
diff --git a/src/bin/psql/startup.c b/src/bin/psql/startup.c
index bb33c7c14d7..20ed28f3db9 100644
--- a/src/bin/psql/startup.c
+++ b/src/bin/psql/startup.c
@@ -135,6 +135,7 @@ main(int argc, char *argv[])
 	pg_logging_set_pre_callback(log_pre_callback);
 	pg_logging_set_locus_callback(log_locus_callback);
 	set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("psql"));
+	pset.output_charset = (getenv("OUTPUT_CHARSET") != NULL);
 
 	if (argc > 1)
 	{