diff --git a/src/coreclr/jit/liveness.cpp b/src/coreclr/jit/liveness.cpp
index 0e415743f561db..f2c31907d4dab9 100644
--- a/src/coreclr/jit/liveness.cpp
+++ b/src/coreclr/jit/liveness.cpp
@@ -93,28 +93,23 @@ void Compiler::fgMarkUseDef(GenTreeLclVarCommon* tree)
 
             if (promotionType != PROMOTION_TYPE_NONE)
             {
-                VARSET_TP bitMask(VarSetOps::MakeEmpty(this));
-
                 for (unsigned i = varDsc->lvFieldLclStart; i < varDsc->lvFieldLclStart + varDsc->lvFieldCnt; ++i)
                 {
-                    noway_assert(lvaTable[i].lvIsStructField);
-                    if (lvaTable[i].lvTracked)
+                    if (!lvaTable[i].lvTracked)
                     {
-                        noway_assert(lvaTable[i].lvVarIndex < lvaTrackedCount);
-                        VarSetOps::AddElemD(this, bitMask, lvaTable[i].lvVarIndex);
+                        continue;
                     }
-                }
 
-                // For pure defs (i.e. not an "update" def which is also a use), add to the (all) def set.
-                if (!isUse)
-                {
-                    assert(isDef);
-                    VarSetOps::UnionD(this, fgCurDefSet, bitMask);
-                }
-                else if (!VarSetOps::IsSubset(this, bitMask, fgCurDefSet))
-                {
-                    // Mark as used any struct fields that are not yet defined.
-                    VarSetOps::UnionD(this, fgCurUseSet, bitMask);
+                    unsigned varIndex = lvaTable[i].lvVarIndex;
+                    if (isUse && !VarSetOps::IsMember(this, fgCurDefSet, varIndex))
+                    {
+                        VarSetOps::AddElemD(this, fgCurUseSet, varIndex);
+                    }
+
+                    if (isDef)
+                    {
+                        VarSetOps::AddElemD(this, fgCurDefSet, varIndex);
+                    }
                 }
             }
         }