diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 9c51384ab92..1f6b24d66f8 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -367,8 +367,9 @@ DoCopy(ParseState *pstate, const CopyStmt *stmt,
 /*
  * Extract the CopyFormatOptions.header_line value from a DefElem.
  *
- * Parses the HEADER option for COPY, which can be a boolean, a non-negative
- * integer (number of lines to skip), or the special value "match".
+ * Parses the HEADER option for COPY, which can be a boolean, an integer greater
+ * than or equal to zero (number of lines to skip), or the special value
+ * "match".
  */
 static int
 defGetCopyHeaderOption(DefElem *def, bool is_from)
@@ -380,8 +381,8 @@ defGetCopyHeaderOption(DefElem *def, bool is_from)
 		return COPY_HEADER_TRUE;
 
 	/*
-	 * Allow 0, 1, "true", "false", "on", "off", a non-negative integer, or
-	 * "match".
+	 * Allow an integer value greater than or equal to zero, "true", "false",
+	 * "on", "off", or "match".
 	 */
 	switch (nodeTag(def->arg))
 	{
@@ -433,9 +434,11 @@ defGetCopyHeaderOption(DefElem *def, bool is_from)
 	}
 	ereport(ERROR,
 			(errcode(ERRCODE_SYNTAX_ERROR),
-			 errmsg("%s requires a Boolean value, a non-negative integer, "
-					"or the string \"match\"",
-					def->defname)));
+	/*- translator: first %s is the name of a COPY option, e.g. ON_ERROR,
+		 second %s is the special value "match" for that option */
+			 errmsg("%s requires a Boolean value, an integer value greater "
+					"than or equal to zero, or the string \"%s\"",
+					def->defname, "match")));
 	return COPY_HEADER_FALSE;	/* keep compiler quiet */
 }
 
diff --git a/src/test/regress/expected/copy.out b/src/test/regress/expected/copy.out
index 24e0f472f14..797fae0e650 100644
--- a/src/test/regress/expected/copy.out
+++ b/src/test/regress/expected/copy.out
@@ -247,7 +247,7 @@ alter table header_copytest add column c text;
 copy header_copytest to stdout with (header match);
 ERROR:  cannot use "match" with HEADER in COPY TO
 copy header_copytest from stdin with (header wrong_choice);
-ERROR:  header requires a Boolean value, a non-negative integer, or the string "match"
+ERROR:  header requires a Boolean value, an integer value greater than or equal to zero, or the string "match"
 -- works
 copy header_copytest from stdin with (header match);
 copy header_copytest (c, a, b) from stdin with (header match);
diff --git a/src/test/regress/expected/copy2.out b/src/test/regress/expected/copy2.out
index f3fdce23459..9c622e760a3 100644
--- a/src/test/regress/expected/copy2.out
+++ b/src/test/regress/expected/copy2.out
@@ -135,7 +135,7 @@ ERROR:  REJECT_LIMIT (0) must be greater than zero
 COPY x from stdin with (header -1);
 ERROR:  a negative integer value cannot be specified for header
 COPY x from stdin with (header 2.5);
-ERROR:  header requires a Boolean value, a non-negative integer, or the string "match"
+ERROR:  header requires a Boolean value, an integer value greater than or equal to zero, or the string "match"
 COPY x to stdout with (header 2);
 ERROR:  cannot use multi-line header in COPY TO
 -- too many columns in column list: should fail