diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/DefaultTaintTracking.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/DefaultTaintTracking.qll
index 4312afa4611..e78d4d5d288 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/DefaultTaintTracking.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/DefaultTaintTracking.qll
@@ -275,7 +275,7 @@ private predicate isChiForAllAliasedMemory(Instruction instr) {
   or
   isChiForAllAliasedMemory(instr.(ChiInstruction).getTotal())
   or
-  isChiForAllAliasedMemory(instr.(PhiInstruction).getAnInput())
+  isChiForAllAliasedMemory(instr.(PhiInstruction).getAnInputOperand().getAnyDef())
 }
 
 private predicate modelTaintToReturnValue(Function f, int parameterIn) {