diff --git a/dlls/d3d8/buffer.c b/dlls/d3d8/buffer.c
index 9eb98bfc2f2..6ab21512472 100644
--- a/dlls/d3d8/buffer.c
+++ b/dlls/d3d8/buffer.c
@@ -198,11 +198,9 @@ static HRESULT WINAPI d3d8_vertexbuffer_Lock(IDirect3DVertexBuffer8 *iface, UINT
 
     wined3d_box.left = offset;
     wined3d_box.right = offset + size;
-    wined3d_mutex_lock();
     wined3d_resource = wined3d_buffer_get_resource(buffer->wined3d_buffer);
     hr = wined3d_resource_map(wined3d_resource, 0, &wined3d_map_desc, &wined3d_box,
             wined3dmapflags_from_d3dmapflags(flags, buffer->usage));
-    wined3d_mutex_unlock();
     *data = wined3d_map_desc.data;
 
     return hr;
@@ -214,9 +212,7 @@ static HRESULT WINAPI d3d8_vertexbuffer_Unlock(IDirect3DVertexBuffer8 *iface)
 
     TRACE("iface %p.\n", iface);
 
-    wined3d_mutex_lock();
     wined3d_resource_unmap(wined3d_buffer_get_resource(buffer->wined3d_buffer), 0);
-    wined3d_mutex_unlock();
 
     return D3D_OK;
 }
@@ -529,11 +525,9 @@ static HRESULT WINAPI d3d8_indexbuffer_Lock(IDirect3DIndexBuffer8 *iface, UINT o
 
     wined3d_box.left = offset;
     wined3d_box.right = offset + size;
-    wined3d_mutex_lock();
     wined3d_resource = wined3d_buffer_get_resource(buffer->wined3d_buffer);
     hr = wined3d_resource_map(wined3d_resource, 0, &wined3d_map_desc, &wined3d_box,
             wined3dmapflags_from_d3dmapflags(flags, buffer->usage));
-    wined3d_mutex_unlock();
     *data = wined3d_map_desc.data;
 
     return hr;
@@ -545,9 +539,7 @@ static HRESULT WINAPI d3d8_indexbuffer_Unlock(IDirect3DIndexBuffer8 *iface)
 
     TRACE("iface %p.\n", iface);
 
-    wined3d_mutex_lock();
     wined3d_resource_unmap(wined3d_buffer_get_resource(buffer->wined3d_buffer), 0);
-    wined3d_mutex_unlock();
 
     return D3D_OK;
 }
diff --git a/dlls/d3d8/surface.c b/dlls/d3d8/surface.c
index c3d28efba20..5fd8cf4d44b 100644
--- a/dlls/d3d8/surface.c
+++ b/dlls/d3d8/surface.c
@@ -269,9 +269,7 @@ static HRESULT WINAPI d3d8_surface_UnlockRect(IDirect3DSurface8 *iface)
 
     TRACE("iface %p.\n", iface);
 
-    wined3d_mutex_lock();
     hr = wined3d_resource_unmap(wined3d_texture_get_resource(surface->wined3d_texture), surface->sub_resource_idx);
-    wined3d_mutex_unlock();
 
     if (hr == WINEDDERR_NOTLOCKED)
     {
diff --git a/dlls/d3d8/volume.c b/dlls/d3d8/volume.c
index 9dc68e850d4..6d0d6f7cb22 100644
--- a/dlls/d3d8/volume.c
+++ b/dlls/d3d8/volume.c
@@ -144,12 +144,10 @@ static HRESULT WINAPI d3d8_volume_LockBox(IDirect3DVolume8 *iface,
     TRACE("iface %p, locked_box %p, box %p, flags %#x.\n",
             iface, locked_box, box, flags);
 
-    wined3d_mutex_lock();
     if (FAILED(hr = wined3d_resource_map(wined3d_texture_get_resource(volume->wined3d_texture),
             volume->sub_resource_idx, &map_desc, (const struct wined3d_box *)box,
             wined3dmapflags_from_d3dmapflags(flags, 0))))
         map_desc.data = NULL;
-    wined3d_mutex_unlock();
 
     locked_box->RowPitch = map_desc.row_pitch;
     locked_box->SlicePitch = map_desc.slice_pitch;
@@ -167,9 +165,7 @@ static HRESULT WINAPI d3d8_volume_UnlockBox(IDirect3DVolume8 *iface)
 
     TRACE("iface %p.\n", iface);
 
-    wined3d_mutex_lock();
     hr = wined3d_resource_unmap(wined3d_texture_get_resource(volume->wined3d_texture), volume->sub_resource_idx);
-    wined3d_mutex_unlock();
 
     if (hr == WINEDDERR_NOTLOCKED)
         return D3DERR_INVALIDCALL;