diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -1489,7 +1489,7 @@
     if (GA) {
       // We are in Case 2 above.
       Idx = Base->getOperand(1);
-      if (!Idx || GA->getNumValues() != 1 || Idx->getNumValues() != 1)
+      if (Idx.isUndef() || GA->getNumValues() != 1)
         return false;
     } else {
       // This might be Case 1 above (or an error)
diff --git a/llvm/test/CodeGen/WebAssembly/externref-tableset.ll b/llvm/test/CodeGen/WebAssembly/externref-tableset.ll
--- a/llvm/test/CodeGen/WebAssembly/externref-tableset.ll
+++ b/llvm/test/CodeGen/WebAssembly/externref-tableset.ll
@@ -79,4 +79,19 @@
   ret void
 }
 
+declare i32 @get_table_slot() local_unnamed_addr
+
+define void @set_externref_table_with_id_from_call(%externref %g) {
+; CHECK-LABEL: set_externref_table_with_id_from_call:
+; CHECK-NEXT:  .functype       set_externref_table_with_id_from_call (externref) -> ()
+; CHECK-NEXT:  call    get_table_slot
+; CHECK-NEXT:  local.get       0
+; CHECK-NEXT:  table.set       externref_table
+; CHECK-NEXT:  end_function
+  %id = call i32 @get_table_slot()
+  %p = getelementptr [0 x %externref], [0 x %externref] addrspace (1)* @externref_table, i32 0, i32 %id
+  store %externref %g, %externref addrspace(1)* %p
+  ret void
+}
+
 ; CHECK: .tabletype externref_table, externref