diff --git a/enzyme/Enzyme/AdjointGenerator.h b/enzyme/Enzyme/AdjointGenerator.h
index f6e5bcc529d3..3ce4f6165215 100644
--- a/enzyme/Enzyme/AdjointGenerator.h
+++ b/enzyme/Enzyme/AdjointGenerator.h
@@ -2747,6 +2747,47 @@ class AdjointGenerator
     auto &DL = gutils->newFunc->getParent()->getDataLayout();
     auto vd = TR.query(MS.getOperand(0)).Data0().ShiftIndices(DL, 0, size, 0);
 
+    if (!vd.isKnownPastPointer()) {
+      // If unknown type results, and zeroing known undef allocation, consider
+      // integers
+      if (auto CI = dyn_cast<ConstantInt>(MS.getOperand(1)))
+        if (CI->isZero()) {
+          auto root = getBaseObject(MS.getOperand(0));
+          bool writtenTo = false;
+          if (isa<AllocaInst>(root) || isAllocationCall(root, gutils->TLI)) {
+            Instruction *cur = MS.getPrevNode();
+            while (cur) {
+              if (cur == root)
+                break;
+              if (auto MCI = dyn_cast<ConstantInt>(MS.getOperand(2))) {
+                if (auto II = dyn_cast<IntrinsicInst>(cur)) {
+                  // If the start of the lifetime for more memory than being
+                  // memset, its valid.
+                  if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
+                    if (getBaseObject(II->getOperand(1)) == root) {
+                      if (auto CI2 = dyn_cast<ConstantInt>(II->getOperand(0))) {
+                        if (MCI->getValue().ult(CI2->getValue()))
+                          break;
+                      }
+                    }
+                  }
+                }
+              }
+              if (cur->mayWriteToMemory()) {
+                writtenTo = true;
+                break;
+              }
+              cur = cur->getPrevNode();
+            }
+
+            if (!writtenTo) {
+              vd = TypeTree(BaseType::Pointer);
+              vd.insert({-1}, BaseType::Integer);
+            }
+          }
+        }
+    }
+
     if (!vd.isKnownPastPointer()) {
       // If unknown type results, consider the intersection of all incoming.
       if (isa<PHINode>(MS.getOperand(0)) || isa<SelectInst>(MS.getOperand(0))) {