diff --git a/src/events/SDL_pen.c b/src/events/SDL_pen.c
index 9a62b4014a..0230249eff 100644
--- a/src/events/SDL_pen.c
+++ b/src/events/SDL_pen.c
@@ -108,17 +108,9 @@ bool SDL_InitPen(void)
 
 void SDL_QuitPen(void)
 {
+    SDL_RemoveAllPenDevices(NULL, NULL);
     SDL_DestroyRWLock(pen_device_rwlock);
     pen_device_rwlock = NULL;
-    if (pen_devices) {
-        for (int i = pen_device_count; i--; ) {
-            SDL_free(pen_devices[i].name);
-        }
-        SDL_free(pen_devices);
-        pen_devices = NULL;
-    }
-    pen_device_count = 0;
-    pen_touching = 0;
 }
 
 #if 0 // not a public API at the moment.
@@ -305,12 +297,16 @@ void SDL_RemoveAllPenDevices(void (*callback)(SDL_PenID instance_id, void *handl
     if (pen_device_count > 0) {
         SDL_assert(pen_devices != NULL);
         for (int i = 0; i < pen_device_count; i++) {
-            callback(pen_devices[i].instance_id, pen_devices[i].driverdata, userdata);
+            if (callback) {
+                callback(pen_devices[i].instance_id, pen_devices[i].driverdata, userdata);
+            }
             SDL_free(pen_devices[i].name);
         }
     }
     SDL_free(pen_devices);
     pen_devices = NULL;
+    pen_device_count = 0;
+    pen_touching = 0;
     SDL_UnlockRWLock(pen_device_rwlock);
 }
 
diff --git a/src/io/SDL_asyncio.c b/src/io/SDL_asyncio.c
index 7696b7bf24..fb21f9171a 100644
--- a/src/io/SDL_asyncio.c
+++ b/src/io/SDL_asyncio.c
@@ -219,7 +219,8 @@ static bool GetAsyncIOTaskOutcome(SDL_AsyncIOTask *task, SDL_AsyncIOOutcome *out
     outcome->userdata = task->app_userdata;
 
     // Take the completed task out of the SDL_AsyncIO that created it.
-    SDL_LockMutex(asyncio->lock);
+    SDL_Mutex *lock = asyncio->lock;
+    SDL_LockMutex(lock);
     LINKED_LIST_UNLINK(task, asyncio);
     // see if it's time to queue a pending close request (close requested and no other pending tasks)
     SDL_AsyncIOTask *closing = asyncio->closing;
@@ -232,7 +233,7 @@ static bool GetAsyncIOTaskOutcome(SDL_AsyncIOTask *task, SDL_AsyncIOOutcome *out
             SDL_AddAtomicInt(&closing->queue->tasks_inflight, -1);
         }
     }
-    SDL_UnlockMutex(task->asyncio->lock);
+    SDL_UnlockMutex(lock);
 
     // was this the result of a closing task? Finally destroy the asyncio.
     bool retval = true;
diff --git a/src/joystick/SDL_gamepad.c b/src/joystick/SDL_gamepad.c
index 03b3faec55..a291ec2694 100644
--- a/src/joystick/SDL_gamepad.c
+++ b/src/joystick/SDL_gamepad.c
@@ -377,6 +377,8 @@ static const char *SDL_UpdateGamepadNameForID(SDL_JoystickID instance_id)
 {
     const char *current_name = NULL;
 
+    SDL_AssertJoysticksLocked();
+
     GamepadMapping_t *mapping = SDL_PrivateGetGamepadMapping(instance_id, true);
     if (mapping) {
         if (SDL_strcmp(mapping->name, "*") == 0) {
@@ -1894,6 +1896,8 @@ static void SDL_UpdateGamepadFaceStyle(SDL_Gamepad *gamepad)
 
 static void SDL_FixupHIDAPIMapping(SDL_Gamepad *gamepad)
 {
+    SDL_AssertJoysticksLocked();
+
     // Check to see if we need fixup
     bool need_fixup = false;
     for (int i = 0; i < gamepad->num_bindings; ++i) {
diff --git a/src/joystick/SDL_joystick.c b/src/joystick/SDL_joystick.c
index 831cc541ca..eb904e8a69 100644
--- a/src/joystick/SDL_joystick.c
+++ b/src/joystick/SDL_joystick.c
@@ -990,6 +990,8 @@ static const char *SDL_UpdateJoystickNameForID(SDL_JoystickID instance_id)
     const char *current_name = NULL;
     const SDL_SteamVirtualGamepadInfo *info;
 
+    SDL_AssertJoysticksLocked();
+
     info = SDL_GetJoystickVirtualGamepadInfoForID(instance_id);
     if (info) {
         current_name = info->name;
@@ -1078,6 +1080,8 @@ static bool SDL_JoystickAxesCenteredAtZero(SDL_Joystick *joystick)
 {
     // printf("JOYSTICK '%s' VID/PID 0x%.4x/0x%.4x AXES: %d\n", joystick->name, vendor, product, joystick->naxes);
 
+    SDL_AssertJoysticksLocked();
+
     if (joystick->naxes == 2) {
         // Assume D-pad or thumbstick style axes are centered at 0
         return true;
@@ -1694,9 +1698,17 @@ int SDL_GetNumJoystickHats(SDL_Joystick *joystick)
  */
 int SDL_GetNumJoystickBalls(SDL_Joystick *joystick)
 {
-    CHECK_JOYSTICK_MAGIC(joystick, -1);
+    int result;
 
-    return joystick->nballs;
+    SDL_LockJoysticks();
+    {
+        CHECK_JOYSTICK_MAGIC(joystick, -1);
+
+        result = joystick->nballs;
+    }
+    SDL_UnlockJoysticks();
+
+    return result;
 }
 
 /*
@@ -2678,6 +2690,8 @@ static void SendSteamHandleUpdateEvents(void)
     SDL_Joystick *joystick;
     const SDL_SteamVirtualGamepadInfo *info;
 
+    SDL_AssertJoysticksLocked();
+
     // Check to see if any Steam handles changed
     for (joystick = SDL_joysticks; joystick; joystick = joystick->next) {
         bool changed = false;
diff --git a/src/joystick/hidapi/SDL_hidapi_gip.c b/src/joystick/hidapi/SDL_hidapi_gip.c
index e4d9d97f30..b357b60f22 100644
--- a/src/joystick/hidapi/SDL_hidapi_gip.c
+++ b/src/joystick/hidapi/SDL_hidapi_gip.c
@@ -2686,6 +2686,8 @@ static GIP_Attachment * HIDAPI_DriverGIP_FindAttachment(SDL_HIDAPI_Device *devic
     GIP_Device *ctx = (GIP_Device *)device->context;
     int i;
 
+    SDL_AssertJoysticksLocked();
+
     for (i = 0; i < MAX_ATTACHMENTS; i++) {
         if (ctx->attachments[i] && ctx->attachments[i]->joystick == joystick->instance_id) {
             return ctx->attachments[i];
diff --git a/src/joystick/hidapi/SDL_hidapi_steam_hori.c b/src/joystick/hidapi/SDL_hidapi_steam_hori.c
index fc61e3f86e..743ab179b8 100644
--- a/src/joystick/hidapi/SDL_hidapi_steam_hori.c
+++ b/src/joystick/hidapi/SDL_hidapi_steam_hori.c
@@ -114,18 +114,18 @@ static bool HIDAPI_DriverSteamHori_OpenJoystick(SDL_HIDAPI_Device *device, SDL_J
     /* Initialize the joystick capabilities */
     joystick->nbuttons = SDL_GAMEPAD_NUM_HORI_BUTTONS;
     joystick->naxes = SDL_GAMEPAD_AXIS_COUNT;
-	joystick->nhats = 1;
+    joystick->nhats = 1;
 
-	ctx->wireless = device->product_id == USB_PRODUCT_HORI_STEAM_CONTROLLER_BT;
+    ctx->wireless = device->product_id == USB_PRODUCT_HORI_STEAM_CONTROLLER_BT;
+
+    if (ctx->wireless && device->serial) {
+        joystick->serial = SDL_strdup(device->serial);
+        ctx->serial_needs_init = false;
+    } else if (!ctx->wireless) {
+        // Need to actual read from the device to init the serial
+        HIDAPI_DriverSteamHori_UpdateDevice(device);
+    }
 
-	if (ctx->wireless && device->serial) {
-		joystick->serial = SDL_strdup(device->serial);
-		ctx->serial_needs_init = false;
-	} else if (!ctx->wireless) {
-		// Need to actual read from the device to init the serial
-		HIDAPI_DriverSteamHori_UpdateDevice(device);
-	}
-       
     SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, 250.0f);
     SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, 250.0f);
 
@@ -275,12 +275,13 @@ static void HIDAPI_DriverSteamHori_HandleStatePacket(SDL_Joystick *joystick, SDL
         SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_HORI_FL, ((data[7] & 0x80) != 0));
     }
 
-	if (!ctx->wireless && ctx->serial_needs_init) {
+    if (!ctx->wireless && ctx->serial_needs_init) {
         char serial[18];
-		(void)SDL_snprintf(serial, sizeof(serial), "%.2x-%.2x-%.2x-%.2x-%.2x-%.2x",
-								data[38], data[39], data[40], data[41], data[42], data[43]);
+        (void)SDL_snprintf(serial, sizeof(serial), "%.2x-%.2x-%.2x-%.2x-%.2x-%.2x",
+                                data[38], data[39], data[40], data[41], data[42], data[43]);
 
-		joystick->serial = SDL_strdup(serial);
+        SDL_AssertJoysticksLocked();
+        joystick->serial = SDL_strdup(serial);
         ctx->serial_needs_init = false;
     }
 
@@ -320,7 +321,6 @@ static void HIDAPI_DriverSteamHori_HandleStatePacket(SDL_Joystick *joystick, SDL
         imu_data[1] = RemapValClamped(-1.0f * LOAD16(data[12], data[13]), INT16_MIN, INT16_MAX, -gyroScale, gyroScale);
         imu_data[2] = RemapValClamped(-1.0f * LOAD16(data[14], data[15]), INT16_MIN, INT16_MAX, -gyroScale, gyroScale);
         imu_data[0] = RemapValClamped(-1.0f * LOAD16(data[16], data[17]), INT16_MIN, INT16_MAX, -gyroScale, gyroScale);
-		
 
         SDL_SendJoystickSensor(timestamp, joystick, SDL_SENSOR_GYRO, sensor_timestamp, imu_data, 3);
 
@@ -334,8 +334,9 @@ static void HIDAPI_DriverSteamHori_HandleStatePacket(SDL_Joystick *joystick, SDL
     if (ctx->last_state[24] != data[24]) {
         bool bCharging = (data[24] & 0x10) != 0;
         int percent = (data[24] & 0xF) * 10;
-		SDL_PowerState state;
-         if (bCharging) {
+        SDL_PowerState state;
+
+        if (bCharging) {
             state = SDL_POWERSTATE_CHARGING;
         } else if (ctx->wireless) {
              state = SDL_POWERSTATE_ON_BATTERY;
diff --git a/src/joystick/hidapi/SDL_hidapi_wii.c b/src/joystick/hidapi/SDL_hidapi_wii.c
index fb3e164a8d..5434141046 100644
--- a/src/joystick/hidapi/SDL_hidapi_wii.c
+++ b/src/joystick/hidapi/SDL_hidapi_wii.c
@@ -512,6 +512,8 @@ static void UpdatePowerLevelWiiU(SDL_Joystick *joystick, Uint8 extensionBatteryB
     bool pluggedIn = !(extensionBatteryByte & 0x04);
     Uint8 batteryLevel = extensionBatteryByte >> 4;
 
+    SDL_AssertJoysticksLocked();
+
     if (pluggedIn) {
         joystick->connection_state = SDL_JOYSTICK_CONNECTION_WIRED;
     } else {
diff --git a/src/joystick/linux/SDL_sysjoystick.c b/src/joystick/linux/SDL_sysjoystick.c
index 6aa66463ef..f0ad06aa9d 100644
--- a/src/joystick/linux/SDL_sysjoystick.c
+++ b/src/joystick/linux/SDL_sysjoystick.c
@@ -1161,6 +1161,8 @@ static SDL_JoystickID LINUX_JoystickGetDeviceInstanceID(int device_index)
 
 static bool allocate_balldata(SDL_Joystick *joystick)
 {
+    SDL_AssertJoysticksLocked();
+
     joystick->hwdata->balls =
         (struct hwdata_ball *)SDL_calloc(joystick->nballs, sizeof(struct hwdata_ball));
     if (joystick->hwdata->balls == NULL) {
@@ -1776,6 +1778,8 @@ static void HandleHat(Uint64 timestamp, SDL_Joystick *stick, int hatidx, int axi
 
 static void HandleBall(SDL_Joystick *stick, Uint8 ball, int axis, int value)
 {
+    SDL_AssertJoysticksLocked();
+
     stick->hwdata->balls[ball].axis[axis] += value;
 }
 
diff --git a/src/video/wayland/SDL_waylandmouse.c b/src/video/wayland/SDL_waylandmouse.c
index 7e3aa255af..1801924897 100644
--- a/src/video/wayland/SDL_waylandmouse.c
+++ b/src/video/wayland/SDL_waylandmouse.c
@@ -545,37 +545,29 @@ static void cursor_frame_done(void *data, struct wl_callback *cb, uint32_t time)
 
 void Wayland_CursorStateSetFrameCallback(SDL_WaylandCursorState *state, void *userdata)
 {
-    if (cursor_thread_context.lock) {
-        SDL_LockMutex(cursor_thread_context.lock);
-    }
+    SDL_LockMutex(cursor_thread_context.lock);
 
     state->frame_callback = wl_surface_frame(state->surface);
     wl_callback_add_listener(state->frame_callback, &cursor_frame_listener, userdata);
 
-    if (cursor_thread_context.lock) {
-        SDL_UnlockMutex(cursor_thread_context.lock);
-    }
+    SDL_UnlockMutex(cursor_thread_context.lock);
 }
 
 void Wayland_CursorStateDestroyFrameCallback(SDL_WaylandCursorState *state)
 {
-    if (cursor_thread_context.lock) {
-        SDL_LockMutex(cursor_thread_context.lock);
-    }
+    SDL_LockMutex(cursor_thread_context.lock);
 
     if (state->frame_callback) {
         wl_callback_destroy(state->frame_callback);
         state->frame_callback = NULL;
     }
 
-    if (cursor_thread_context.lock) {
-        SDL_UnlockMutex(cursor_thread_context.lock);
-    }
+    SDL_UnlockMutex(cursor_thread_context.lock);
 }
 
 static void Wayland_CursorStateResetAnimation(SDL_WaylandCursorState *state, bool lock)
 {
-    if (lock && cursor_thread_context.lock) {
+    if (lock) {
         SDL_LockMutex(cursor_thread_context.lock);
     }
 
@@ -583,7 +575,7 @@ static void Wayland_CursorStateResetAnimation(SDL_WaylandCursorState *state, boo
     state->current_frame_time_ms = 0;
     state->current_frame = 0;
 
-    if (lock && cursor_thread_context.lock) {
+    if (lock) {
         SDL_UnlockMutex(cursor_thread_context.lock);
     }
 }