diff --git a/erlang/apps/sim/src/sim_boolean.erl b/erlang/apps/sim/src/sim_boolean.erl
index 2155aa2..94ec657 100644
--- a/erlang/apps/sim/src/sim_boolean.erl
+++ b/erlang/apps/sim/src/sim_boolean.erl
@@ -43,6 +43,7 @@
         , handle_SETZB/4
         , handle_SETZM/4
         , handle_XOR/4
+        , handle_XORI/4
         ]).
 
 -include("sim_core.hrl").
@@ -306,6 +307,14 @@ handle_XOR(Core, Mem, IR, EA) ->
                           fun(Core1, Mem1) -> handle_XOR(Core1, Mem1, IR, EA) end)
   end.
 
+-spec handle_XORI(#core{}, sim_mem:mem(), IR :: word(), #ea{})
+      -> {#core{}, sim_mem:mem(), {ok, integer()} | {error, {module(), term()}}}.
+handle_XORI(Core, Mem, IR, EA) ->
+  AC = IR band 8#17,
+  CA = sim_core:get_ac(Core, AC),
+  Word = CA bxor EA#ea.offset,
+  sim_core:next_pc(sim_core:set_ac(Core, AC, Word), Mem).
+
 %% Miscellaneous ===============================================================
 
 ea_address(#ea{section = Section, offset = Offset}) ->
diff --git a/erlang/apps/sim/src/sim_core.erl b/erlang/apps/sim/src/sim_core.erl
index e1c99d8..fc92978 100644
--- a/erlang/apps/sim/src/sim_core.erl
+++ b/erlang/apps/sim/src/sim_core.erl
@@ -278,6 +278,7 @@ dispatch(Core, Mem, IR, EA) ->
     8#426 -> sim_moves:handle_MOVEM(Core, Mem, IR, EA); % SETAM = MOVEM
     8#427 -> sim_moves:handle_MOVEM(Core, Mem, IR, EA); % SETAB = MOVEM
     8#430 -> sim_boolean:handle_XOR(Core, Mem, IR, EA);
+    8#431 -> sim_boolean:handle_XORI(Core, Mem, IR, EA);
     _ ->
       PC = (Core#core.pc_section bsl 18) bor Core#core.pc_offset,
       {Core, Mem, {error, {?MODULE, {dispatch, PC, IR, EA}}}}
diff --git a/erlang/apps/sim/test/sim_boolean_tests.erl b/erlang/apps/sim/test/sim_boolean_tests.erl
index 591dca1..72febb4 100644
--- a/erlang/apps/sim/test/sim_boolean_tests.erl
+++ b/erlang/apps/sim/test/sim_boolean_tests.erl
@@ -69,6 +69,7 @@
 -define(OP_SETAM, 8#426).
 -define(OP_SETAB, 8#426).
 -define(OP_XOR, 8#430).
+-define(OP_XORI, 8#431).
 
 %% 2.4 Boolean Functions =======================================================
 
@@ -388,6 +389,16 @@ xor_test() ->
          [ {#ea{section = 1, offset = 1, islocal = false}, 8#434343} % AC1 = 0,,434343
          ]).
 
+xori_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 1, 0, 0, 8#707070)} % 1,,100/ MOVEI 1,707070
+    , {1, 8#101, ?INSN(?OP_XORI, 1, 0, 0, 8#333333)}  % 1,,101/ XORI 1,333333
+    , {1, 8#102, ?INSN_INVALID}                       % 1,,102/ <invalid>
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 1, islocal = false}, 8#434343} % AC1 = 0,,434343
+         ]).
+
 %% Common code to run short sequences ==========================================
 
 expect(Prog, ACs, ExpectedPC, ExpectedFlags, ExpectedEs) ->