diff --git a/src/pyrad3/dictionary.py b/src/pyrad3/dictionary.py
index 71ec478..115cb15 100644
--- a/src/pyrad3/dictionary.py
+++ b/src/pyrad3/dictionary.py
@@ -454,7 +454,7 @@ class Dictionary:
         self.cur_vendor.attrs[attrcode] = attribute
 
         if self.cur_vendor != self.rfc_vendor:
-            codes = [26] + codes
+            codes = [26, self.cur_vendor.code] + codes
         attrcode = codes[0] if len(codes) == 1 else tuple(codes)
         self.attrindex[attrcode] = attribute
         self.attrindex[name] = attribute
diff --git a/tests/test_dictionary.py b/tests/test_dictionary.py
index 6271329..98feb83 100644
--- a/tests/test_dictionary.py
+++ b/tests/test_dictionary.py
@@ -377,3 +377,34 @@ def test_invalid_attribute_flags(invalid_flag):
     dictionary = StringIO(f"ATTRIBUTE NAME 123 octets {invalid_flag}")
     with pytest.raises(ParseError):
         Dictionary("", dictionary)
+
+
+@pytest.mark.parametrize(
+    "attribute", ["RFC-ATTRIBUTE", "VENDOR-ATTRIBUTE", 7, (26, 5555, 7)]
+)
+def test_get_attributes_from_dictionaries(attribute):
+    dictionary = StringIO(
+        "ATTRIBUTE RFC-ATTRIBUTE 7 integer\n"
+        "VENDOR TEST-VENDOR 5555\n"
+        "BEGIN-VENDOR TEST-VENDOR\n"
+        "ATTRIBUTE VENDOR-ATTRIBUTE 7 integer\n"
+        "END-VENDOR TEST-VENDOR"
+    )
+    dd = Dictionary("", dictionary)
+    _ = dd[attribute]
+
+
+@pytest.mark.parametrize(
+    "attribute", ["RFC-ATTRIBUTE1", 8, (26, 5556, 7), (26, 5555, 8)]
+)
+def test_get_nonexisting_attributes_from_dictionaries(attribute):
+    dictionary = StringIO(
+        "ATTRIBUTE RFC-ATTRIBUTE 7 integer\n"
+        "VENDOR TEST-VENDOR 5555\n"
+        "BEGIN-VENDOR TEST-VENDOR\n"
+        "ATTRIBUTE VENDOR-ATTRIBUTE 7 integer\n"
+        "END-VENDOR TEST-VENDOR"
+    )
+    dd = Dictionary("", dictionary)
+    with pytest.raises(KeyError):
+        _ = dd[attribute]