diff --git a/tests/bugs/gh_8304_test.py b/tests/bugs/gh_8304_test.py
new file mode 100644
index 00000000..6260f53e
--- /dev/null
+++ b/tests/bugs/gh_8304_test.py
@@ -0,0 +1,96 @@
+#coding:utf-8
+
+"""
+ID:          issue-8304
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/8304
+TITLE:       wrong results using minvalue/maxvalue in join condition
+DESCRIPTION:
+NOTES:
+    [04.11.2024] pzotov
+    Confirmed bug on 6.0.0.515-d53f368 (dob: 30.10.2024).
+    Checked on 6.0.0.515-1c3dc43; 5.0.2.1551-90fdb97; 4.0.6.3165 (intermediate build).
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = """
+    create domain dm_sml smallint default 0 not null;
+    create domain dm_txt varchar(100) not null;
+    create table tbl1 (
+        ds int,
+        ru dm_sml,
+        wi dm_sml,
+        ko dm_sml
+    );
+
+    create table tbl2 (
+        id     int,
+        ru     dm_sml,
+        ru_txt dm_txt,
+        wi     dm_sml,
+        wi_txt dm_txt,
+        ko     dm_sml,
+        ko_txt dm_txt
+    );
+
+    commit;
+
+    insert into tbl1 (ds, ru, wi, ko) values(50, 1, 1, 0);
+
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(1, 1, 'a', 1, 'a', 1, 'a');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(2, 1, 'b', 1, 'b', 0, 'b');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(3, 1, 'c', 0, 'c', 1, 'c');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(4, 1, 'd', 0, 'd', 0, 'd');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(5, 0, 'e', 1, 'e', 1, 'e');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(6, 0, 'f', 1, 'f', 0, 'f');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(7, 0, 'g', 0, 'g', 1, 'g');
+    insert into tbl2 (id, ru, ru_txt, wi, wi_txt, ko, ko_txt) values(8, 0, 'h', 0, 'h', 0, 'h');
+
+    commit;
+
+    set count on;
+    set list on;
+
+    -- no record - wrong:
+    select 'case-1' as msg, a.*
+    from tbl1 a
+    join tbl2 b on minvalue(a.ko, 1) = b.ko and
+                   minvalue(a.ru, 1) = b.ru and
+                   minvalue(a.wi, 1) = b.wi
+    ;
+
+    -- one record - correct:
+    select 'case-2' as msg, a.*
+    from tbl1 a
+    join tbl2 b on decode(a.ko, 0, 0, 1) = b.ko and
+                   decode(a.ru, 0, 0, 1) = b.ru and
+                   decode(a.wi, 0, 0, 1) = b.wi
+    ;
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    MSG                             case-1
+    DS                              50
+    RU                              1
+    WI                              1
+    KO                              0
+    Records affected: 1
+
+    MSG                             case-2
+    DS                              50
+    RU                              1
+    WI                              1
+    KO                              0
+    Records affected: 1
+"""
+
+@pytest.mark.version('>=4.0.6')
+def test_1(act: Action):
+    act.expected_stdout = expected_stdout
+    act.execute(combine_output = True)
+    assert act.clean_stdout == act.clean_expected_stdout