diff --git a/named_args.go b/named_args.go
index e6906b3b..3d91367b 100644
--- a/named_args.go
+++ b/named_args.go
@@ -128,7 +128,7 @@ func namedArgState(l *sqlLexer) stateFn {
 				l.start = l.pos
 			}
 			return nil
-		} else if !(isLetter(r) || (r >= '0' && r <= '9')) {
+		} else if !(isLetter(r) || (r >= '0' && r <= '9') || r == '_') {
 			l.pos -= width
 			na := namedArg(l.src[l.start:l.pos])
 			if _, found := l.nameToOrdinal[na]; !found {
diff --git a/named_args_test.go b/named_args_test.go
index fea3b897..116e03dc 100644
--- a/named_args_test.go
+++ b/named_args_test.go
@@ -36,6 +36,12 @@ func TestNamedArgsRewriteQuery(t *testing.T) {
 			expectedSQL:  "select $1::int, $2::text",
 			expectedArgs: []any{int32(42), "foo"},
 		},
+		{
+			sql:          "select @Abc::int, @b_4::text",
+			namedArgs:    pgx.NamedArgs{"Abc": int32(42), "b_4": "foo"},
+			expectedSQL:  "select $1::int, $2::text",
+			expectedArgs: []any{int32(42), "foo"},
+		},
 		{
 			sql:          "at end @",
 			namedArgs:    pgx.NamedArgs{"a": int32(42), "b": "foo"},