diff --git a/Core/gb.c b/Core/gb.c
index ab35b78..2afeb81 100644
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -1151,6 +1151,9 @@ uint8_t GB_run(GB_gameboy_t *gb)
         GB_debugger_handle_async_commands(gb);
         GB_rewind_push(gb);
     }
+    if (!(gb->io_registers[GB_IO_IF] & 0x10) && (gb->io_registers[GB_IO_JOYP] & 0x30) != 0x30) {
+        gb->joyp_accessed = true;
+    }
     return gb->cycles_since_run;
 }
 
diff --git a/Core/gb.h b/Core/gb.h
index e5bb128..0a3b5da 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -632,7 +632,8 @@ struct GB_gameboy_internal_s {
         bool has_sgb_border;
         bool objects_disabled;
         bool background_disabled;
-               
+        bool joyp_accessed;
+
         /* Timing */
         uint64_t last_sync;
         uint64_t cycles_since_last_sync; // In 8MHz units
diff --git a/Core/joypad.c b/Core/joypad.c
index 06fb53f..f16aa9e 100644
--- a/Core/joypad.c
+++ b/Core/joypad.c
@@ -121,3 +121,13 @@ void GB_set_key_mask_for_player(GB_gameboy_t *gb, GB_key_mask_t mask, unsigned p
     
     GB_update_joyp(gb);
 }
+
+bool GB_get_joyp_accessed(GB_gameboy_t *gb)
+{
+    return gb->joyp_accessed;
+}
+
+void GB_clear_joyp_accessed(GB_gameboy_t *gb)
+{
+    gb->joyp_accessed = false;
+}
diff --git a/Core/joypad.h b/Core/joypad.h
index beb532e..a360af1 100644
--- a/Core/joypad.h
+++ b/Core/joypad.h
@@ -34,6 +34,9 @@ void GB_set_key_state_for_player(GB_gameboy_t *gb, GB_key_t index, unsigned play
 void GB_set_key_mask(GB_gameboy_t *gb, GB_key_mask_t mask);
 void GB_set_key_mask_for_player(GB_gameboy_t *gb, GB_key_mask_t mask, unsigned player);
 void GB_icd_set_joyp(GB_gameboy_t *gb, uint8_t value);
+bool GB_get_joyp_accessed(GB_gameboy_t *gb);
+void GB_clear_joyp_accessed(GB_gameboy_t *gb);
+
 
 #ifdef GB_INTERNAL
 internal void GB_update_joyp(GB_gameboy_t *gb);
diff --git a/Core/memory.c b/Core/memory.c
index 7ca770a..43a9dde 100644
--- a/Core/memory.c
+++ b/Core/memory.c
@@ -568,6 +568,7 @@ static uint8_t read_high_memory(GB_gameboy_t *gb, uint16_t addr)
                 return ((gb->apu.is_active[GB_NOISE] ? (gb->apu.samples[GB_NOISE] << 4) : 0) |
                         (gb->apu.is_active[GB_WAVE] ? (gb->apu.samples[GB_WAVE]) : 0))  & (gb->model <= GB_MODEL_CGB_C? gb->apu.pcm_mask[1] : 0xFF);
             case GB_IO_JOYP:
+                gb->joyp_accessed = true;
                 GB_timing_sync(gb);
             case GB_IO_TMA:
             case GB_IO_LCDC:
diff --git a/Core/sm83_cpu.c b/Core/sm83_cpu.c
index 035779b..130bfb3 100644
--- a/Core/sm83_cpu.c
+++ b/Core/sm83_cpu.c
@@ -363,6 +363,9 @@ static void leave_stop_mode(GB_gameboy_t *gb)
 static void stop(GB_gameboy_t *gb, uint8_t opcode)
 {
     flush_pending_cycles(gb);
+    if ((gb->io_registers[GB_IO_JOYP] & 0x30) != 0x30) {
+        gb->joyp_accessed = true;
+    }
     bool exit_by_joyp = ((gb->io_registers[GB_IO_JOYP] & 0xF) != 0xF);
     bool speed_switch = (gb->io_registers[GB_IO_KEY1] & 0x1) && !exit_by_joyp;
     bool immediate_exit = speed_switch || exit_by_joyp;
@@ -1575,6 +1578,9 @@ void GB_cpu_run(GB_gameboy_t *gb)
     if (gb->stopped) {
         GB_timing_sync(gb);
         GB_advance_cycles(gb, 4);
+        if ((gb->io_registers[GB_IO_JOYP] & 0x30) != 0x30) {
+            gb->joyp_accessed = true;
+        }
         if ((gb->io_registers[GB_IO_JOYP] & 0xF) != 0xF) {
             leave_stop_mode(gb);
             GB_advance_cycles(gb, 8);