diff --git a/renderdoc/driver/d3d12/d3d12_device.cpp b/renderdoc/driver/d3d12/d3d12_device.cpp
index 2add2afea..989aa0d09 100644
--- a/renderdoc/driver/d3d12/d3d12_device.cpp
+++ b/renderdoc/driver/d3d12/d3d12_device.cpp
@@ -1659,11 +1659,11 @@ void WrappedID3D12Device::Unmap(ID3D12Resource *Resource, UINT Subresource, byte
   if(heapProps.Type == D3D12_HEAP_TYPE_READBACK)
     return;
 
+  map.res = Resource;
+  map.subres = Subresource;
+
   {
     SCOPED_LOCK(m_MapsLock);
-    map.res = Resource;
-    map.subres = Subresource;
-
     int32_t idx = m_Maps.indexOf(map);
 
     if(idx < 0)
@@ -2481,14 +2481,12 @@ bool WrappedID3D12Device::EndFrameCapture(DeviceOwnedWindow devWnd)
     m_State = CaptureState::BackgroundCapturing;
 
     GPUSync();
-
-    {
-      SCOPED_LOCK(m_MapsLock);
-      for(auto it = m_Maps.begin(); it != m_Maps.end(); ++it)
-        GetWrapped(it->res)->FreeShadow();
-    }
   }
 
+  rdcarray<MapState> maps = GetMaps();
+  for(auto it = maps.begin(); it != maps.end(); ++it)
+    GetWrapped(it->res)->FreeShadow();
+
   const uint32_t maxSize = 2048;
   RenderDoc::FramePixels fp;
 
@@ -2834,15 +2832,13 @@ bool WrappedID3D12Device::DiscardFrameCapture(DeviceOwnedWindow devWnd)
 
     GPUSync();
 
-    {
-      SCOPED_LOCK(m_MapsLock);
-      for(auto it = m_Maps.begin(); it != m_Maps.end(); ++it)
-        GetWrapped(it->res)->FreeShadow();
-    }
-
     queues = m_Queues;
   }
 
+  rdcarray<MapState> maps = GetMaps();
+  for(auto it = maps.begin(); it != maps.end(); ++it)
+    GetWrapped(it->res)->FreeShadow();
+
   m_HeaderChunk->Delete();
   m_HeaderChunk = NULL;
 
diff --git a/renderdoc/driver/d3d12/d3d12_resources.cpp b/renderdoc/driver/d3d12/d3d12_resources.cpp
index b56b47721..fc59c5940 100644
--- a/renderdoc/driver/d3d12/d3d12_resources.cpp
+++ b/renderdoc/driver/d3d12/d3d12_resources.cpp
@@ -179,8 +179,6 @@ WrappedID3D12Resource::~WrappedID3D12Resource()
 
 byte *WrappedID3D12Resource::GetMap(UINT Subresource)
 {
-  SCOPED_LOCK(GetResourceRecord()->m_MapLock);
-
   D3D12ResourceRecord::MapData *map = GetResourceRecord()->m_Maps;
   size_t mapcount = GetResourceRecord()->m_MapsCount;
 
@@ -192,8 +190,6 @@ byte *WrappedID3D12Resource::GetMap(UINT Subresource)
 
 byte *WrappedID3D12Resource::GetShadow(UINT Subresource)
 {
-  SCOPED_LOCK(GetResourceRecord()->m_MapLock);
-
   D3D12ResourceRecord::MapData *map = GetResourceRecord()->m_Maps;
 
   return map[Subresource].shadowPtr;
@@ -201,8 +197,6 @@ byte *WrappedID3D12Resource::GetShadow(UINT Subresource)
 
 void WrappedID3D12Resource::AllocShadow(UINT Subresource, size_t size)
 {
-  SCOPED_LOCK(GetResourceRecord()->m_MapLock);
-
   D3D12ResourceRecord::MapData *map = GetResourceRecord()->m_Maps;
 
   if(map[Subresource].shadowPtr == NULL)