diff --git a/renderdoc/driver/d3d11/d3d11_context_wrap.cpp b/renderdoc/driver/d3d11/d3d11_context_wrap.cpp
index 3b19ae983..60edd22d6 100644
--- a/renderdoc/driver/d3d11/d3d11_context_wrap.cpp
+++ b/renderdoc/driver/d3d11/d3d11_context_wrap.cpp
@@ -7300,13 +7300,13 @@ void MapIntercept::Init(ID3D11Texture1D *tex, UINT sub, void *appMemory)
 
   int mip = GetMipForSubresource(tex, sub);
 
-  // a row in block formats is a row of 4x4 blocks.
-  if(IsBlockFormat(fmt))
-    numRows /= 4;
-
   numRows = RDCMAX(1, numRows >> mip);
   numSlices = RDCMAX(1, numSlices >> mip);
 
+  // a row in block formats is a row of 4x4 blocks.
+  if(IsBlockFormat(fmt))
+    numRows = AlignUp4(numRows) / 4;
+
   if(IsYUVPlanarFormat(fmt))
     numRows = GetYUVNumRows(fmt, numRows);
 
@@ -7335,13 +7335,13 @@ void MapIntercept::Init(ID3D11Texture2D *tex, UINT sub, void *appMemory)
 
   int mip = GetMipForSubresource(tex, sub);
 
-  // a row in block formats is a row of 4x4 blocks.
-  if(IsBlockFormat(fmt))
-    numRows /= 4;
-
   numRows = RDCMAX(1, numRows >> mip);
   numSlices = RDCMAX(1, numSlices >> mip);
 
+  // a row in block formats is a row of 4x4 blocks.
+  if(IsBlockFormat(fmt))
+    numRows = AlignUp4(numRows) / 4;
+
   if(IsYUVPlanarFormat(fmt))
     numRows = GetYUVNumRows(fmt, numRows);
 
@@ -7369,13 +7369,13 @@ void MapIntercept::Init(ID3D11Texture3D *tex, UINT sub, void *appMemory)
 
   int mip = GetMipForSubresource(tex, sub);
 
-  // a row in block formats is a row of 4x4 blocks.
-  if(IsBlockFormat(fmt))
-    numRows /= 4;
-
   numRows = RDCMAX(1, numRows >> mip);
   numSlices = RDCMAX(1, numSlices >> mip);
 
+  // a row in block formats is a row of 4x4 blocks.
+  if(IsBlockFormat(fmt))
+    numRows = AlignUp4(numRows) / 4;
+
   if(IsYUVPlanarFormat(fmt))
     numRows = GetYUVNumRows(fmt, numRows);