diff --git a/rust/ql/lib/codeql/rust/internal/typeinference/FunctionType.qll b/rust/ql/lib/codeql/rust/internal/typeinference/FunctionType.qll
index aeb186c0cdcb..74d8385bdf20 100644
--- a/rust/ql/lib/codeql/rust/internal/typeinference/FunctionType.qll
+++ b/rust/ql/lib/codeql/rust/internal/typeinference/FunctionType.qll
@@ -419,14 +419,21 @@ module ArgsAreInstantiationsOf<ArgsAreInstantiationsOfInputSig Input> {
   private module ArgIsInstantiationOfToIndex =
     ArgIsInstantiationOf<CallAndPos, ArgIsInstantiationOfToIndexInput>;
 
+  pragma[nomagic]
+  private predicate argIsInstantiationOf(
+    Input::Call call, FunctionPosition pos, ImplOrTraitItemNode i, Function f, int rnk
+  ) {
+    ArgIsInstantiationOfToIndex::argIsInstantiationOf(MkCallAndPos(call, pos), i, _) and
+    toCheckRanked(i, f, _, pos, rnk)
+  }
+
   pragma[nomagic]
   private predicate argsAreInstantiationsOfToIndex(
     Input::Call call, ImplOrTraitItemNode i, Function f, int rnk
   ) {
     exists(FunctionPosition pos |
-      ArgIsInstantiationOfToIndex::argIsInstantiationOf(MkCallAndPos(call, pos), i, _) and
-      call.hasTargetCand(i, f) and
-      toCheckRanked(i, f, _, pos, rnk)
+      argIsInstantiationOf(call, pos, i, f, rnk) and
+      call.hasTargetCand(i, f)
     |
       rnk = 0
       or