diff --git a/doc/src/sgml/ref/vacuumdb.sgml b/doc/src/sgml/ref/vacuumdb.sgml
index eeafed7fbe..61c2e7d237 100644
--- a/doc/src/sgml/ref/vacuumdb.sgml
+++ b/doc/src/sgml/ref/vacuumdb.sgml
@@ -230,11 +230,11 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
-      <term><option>-P <replaceable class="parameter">parallel_degree</replaceable></option></term>
-      <term><option>--parallel=<replaceable class="parameter">parallel_degree</replaceable></option></term>
+      <term><option>-P <replaceable class="parameter">parallel_workers</replaceable></option></term>
+      <term><option>--parallel=<replaceable class="parameter">parallel_workers</replaceable></option></term>
       <listitem>
        <para>
-        Specify the parallel degree of <firstterm>parallel vacuum</firstterm>.
+        Specify the number of parallel workers for <firstterm>parallel vacuum</firstterm>.
         This allows the vacuum to leverage multiple CPUs to process indexes.
         See <xref linkend="sql-vacuum"/>.
        </para>
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 92c4eb6a87..5ef6698790 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -160,7 +160,7 @@ ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel)
 				if (nworkers < 0 || nworkers > MAX_PARALLEL_WORKER_LIMIT)
 					ereport(ERROR,
 							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("parallel vacuum degree must be between 0 and %d",
+							 errmsg("parallel workers for vacuum must be between 0 and %d",
 									MAX_PARALLEL_WORKER_LIMIT),
 							 parser_errposition(pstate, opt->location)));
 
diff --git a/src/bin/scripts/vacuumdb.c b/src/bin/scripts/vacuumdb.c
index 3e57fa9a86..1cf689cd05 100644
--- a/src/bin/scripts/vacuumdb.c
+++ b/src/bin/scripts/vacuumdb.c
@@ -189,7 +189,7 @@ main(int argc, char *argv[])
 				vacopts.parallel_workers = atoi(optarg);
 				if (vacopts.parallel_workers < 0)
 				{
-					pg_log_error("parallel vacuum degree must be a non-negative integer");
+					pg_log_error("parallel workers for vacuum must be greater than or equal to zero");
 					exit(1);
 				}
 				break;
@@ -920,7 +920,7 @@ help(const char *progname)
 	printf(_("  -j, --jobs=NUM                  use this many concurrent connections to vacuum\n"));
 	printf(_("      --min-mxid-age=MXID_AGE     minimum multixact ID age of tables to vacuum\n"));
 	printf(_("      --min-xid-age=XID_AGE       minimum transaction ID age of tables to vacuum\n"));
-	printf(_("  -P, --parallel=PARALLEL_DEGREE  use this many background workers for vacuum, if available\n"));
+	printf(_("  -P, --parallel=PARALLEL_WORKERS use this many background workers for vacuum, if available\n"));
 	printf(_("  -q, --quiet                     don't write any messages\n"));
 	printf(_("      --skip-locked               skip relations that cannot be immediately locked\n"));
 	printf(_("  -t, --table='TABLE[(COLUMNS)]'  vacuum specific table(s) only\n"));
diff --git a/src/test/regress/expected/vacuum.out b/src/test/regress/expected/vacuum.out
index 3fccb183c0..d026847c15 100644
--- a/src/test/regress/expected/vacuum.out
+++ b/src/test/regress/expected/vacuum.out
@@ -110,7 +110,7 @@ VACUUM (PARALLEL 2) pvactst;
 UPDATE pvactst SET i = i WHERE i < 1000;
 VACUUM (PARALLEL 0) pvactst; -- disable parallel vacuum
 VACUUM (PARALLEL -1) pvactst; -- error
-ERROR:  parallel vacuum degree must be between 0 and 1024
+ERROR:  parallel workers for vacuum must be between 0 and 1024
 LINE 1: VACUUM (PARALLEL -1) pvactst;
                 ^
 VACUUM (PARALLEL 2, INDEX_CLEANUP FALSE) pvactst;