diff --git a/infer/src/cost/cost.ml b/infer/src/cost/cost.ml
index 184411f28..6a12d2d3d 100644
--- a/infer/src/cost/cost.ml
+++ b/infer/src/cost/cost.ml
@@ -62,12 +62,22 @@ module InstrBasicCostWithReason = struct
         && Procdesc.is_objc_arc_on callee_pdesc )
 
 
+  let get_modeled_cost_unless_top ~default modeled_cost =
+    if BasicCost.is_top modeled_cost then
+      (* If we get Top modeled cost, this could cause
+         Top-poisoning up the call chain, so instead, we keep
+         underestimating the cost as we do with the case where we
+         have no summary below.*)
+      default
+    else BasicCostWithReason.of_basic_cost modeled_cost
+
+
   let dispatch_operation tenv callee_pname callee_cost_opt fun_arg_list get_summary model_env ret
       inferbo_mem =
     match CostModels.Call.dispatch tenv callee_pname fun_arg_list with
     | Some model ->
-        BasicCostWithReason.of_basic_cost
-          (model {get_summary; model_env= Lazy.force model_env} ~ret inferbo_mem)
+        let modeled_cost = model {get_summary; model_env= Lazy.force model_env} ~ret inferbo_mem in
+        get_modeled_cost_unless_top ~default:(BasicCostWithReason.one ()) modeled_cost
     | None -> (
       match callee_cost_opt with
       | Some callee_cost ->
@@ -83,31 +93,33 @@ module InstrBasicCostWithReason = struct
   let dispatch_autoreleasepool tenv callee_pname callee_cost_opt fun_arg_list
       ({get_summary} as extras) model_env ((_, ret_typ) as ret) cfg loc inferbo_mem :
       BasicCostWithReason.t =
+    let fun_cost =
+      if
+        is_objc_call_from_no_arc_to_arc extras cfg callee_pname
+        && Typ.is_pointer_to_objc_non_tagged_class ret_typ
+        && not (return_object_owned_by_caller callee_pname)
+      then
+        let autoreleasepool_trace =
+          Bounds.BoundTrace.of_arc_from_non_arc (Procname.to_string callee_pname) loc
+        in
+        BasicCostWithReason.one ~autoreleasepool_trace ()
+      else BasicCostWithReason.zero
+    in
     match CostAutoreleaseModels.Call.dispatch tenv callee_pname fun_arg_list with
     | Some model ->
         let autoreleasepool_size =
           model {get_summary; model_env= Lazy.force model_env} ~ret inferbo_mem
         in
-        BasicCostWithReason.of_basic_cost autoreleasepool_size
+        get_modeled_cost_unless_top ~default:fun_cost autoreleasepool_size
     | None ->
-        let fun_cost =
-          if
-            is_objc_call_from_no_arc_to_arc extras cfg callee_pname
-            && Typ.is_pointer_to_objc_non_tagged_class ret_typ
-            && not (return_object_owned_by_caller callee_pname)
-          then
-            let autoreleasepool_trace =
-              Bounds.BoundTrace.of_arc_from_non_arc (Procname.to_string callee_pname) loc
-            in
-            BasicCostWithReason.one ~autoreleasepool_trace ()
-          else BasicCostWithReason.zero
-        in
         Option.value_map ~default:fun_cost ~f:(BasicCostWithReason.plus fun_cost) callee_cost_opt
 
 
   let dispatch_allocation tenv callee_pname callee_cost_opt : BasicCostWithReason.t =
     CostAllocationModels.ProcName.dispatch tenv callee_pname
-    |> Option.value ~default:(Option.value callee_cost_opt ~default:BasicCostWithReason.zero)
+    |> Option.value_map ~default:(Option.value callee_cost_opt ~default:BasicCostWithReason.zero)
+         ~f:(fun modeled_cost ->
+           get_modeled_cost_unless_top ~default:BasicCostWithReason.zero modeled_cost )
 
 
   let dispatch_func_ptr_call {inferbo_invariant_map; integer_type_widths} instr_node fun_exp
diff --git a/infer/src/cost/costAllocationModels.ml b/infer/src/cost/costAllocationModels.ml
index 1f75e3866..5c0921b4c 100644
--- a/infer/src/cost/costAllocationModels.ml
+++ b/infer/src/cost/costAllocationModels.ml
@@ -6,16 +6,16 @@
  *)
 
 open! IStd
-module BasicCostWithReason = CostDomain.BasicCostWithReason
+module BasicCost = CostDomain.BasicCost
 
 module ProcName = struct
-  let dispatch : (Tenv.t, BasicCostWithReason.t, unit) ProcnameDispatcher.ProcName.dispatcher =
+  let dispatch : (Tenv.t, BasicCost.t, unit) ProcnameDispatcher.ProcName.dispatcher =
     let open ProcnameDispatcher.ProcName in
     let match_builtin builtin _ s = String.equal s (Procname.get_method builtin) in
     make_dispatcher
-      [ +match_builtin BuiltinDecl.__new <>--> BasicCostWithReason.one ()
-      ; +match_builtin BuiltinDecl.__new_array <>--> BasicCostWithReason.one ()
-      ; +match_builtin BuiltinDecl.__objc_alloc_no_fail <>--> BasicCostWithReason.one ()
-      ; +match_builtin BuiltinDecl.malloc <>--> BasicCostWithReason.one ()
-      ; +match_builtin BuiltinDecl.malloc_no_fail <>--> BasicCostWithReason.one () ]
+      [ +match_builtin BuiltinDecl.__new <>--> BasicCost.one ()
+      ; +match_builtin BuiltinDecl.__new_array <>--> BasicCost.one ()
+      ; +match_builtin BuiltinDecl.__objc_alloc_no_fail <>--> BasicCost.one ()
+      ; +match_builtin BuiltinDecl.malloc <>--> BasicCost.one ()
+      ; +match_builtin BuiltinDecl.malloc_no_fail <>--> BasicCost.one () ]
 end
diff --git a/infer/src/cost/costAllocationModels.mli b/infer/src/cost/costAllocationModels.mli
index 33db4f627..5df794c6b 100644
--- a/infer/src/cost/costAllocationModels.mli
+++ b/infer/src/cost/costAllocationModels.mli
@@ -8,6 +8,5 @@
 open! IStd
 
 module ProcName : sig
-  val dispatch :
-    (Tenv.t, CostDomain.BasicCostWithReason.t, unit) ProcnameDispatcher.ProcName.dispatcher
+  val dispatch : (Tenv.t, CostDomain.BasicCost.t, unit) ProcnameDispatcher.ProcName.dispatcher
 end
diff --git a/infer/tests/codetoanalyze/objc/performance/NSString.m b/infer/tests/codetoanalyze/objc/performance/NSString.m
index 25be4dab7..63517e683 100644
--- a/infer/tests/codetoanalyze/objc/performance/NSString.m
+++ b/infer/tests/codetoanalyze/objc/performance/NSString.m
@@ -129,7 +129,7 @@ bool string_has_prefix_linear(NSString* str, NSString* prefix) {
 
 @implementation DummyClass
 
-+ (void)call_string_by_appending_string_constant_FP {
++ (void)call_string_by_appending_string_constant {
   NSString* s = [NSStringFromClass(self) stringByAppendingString:@"abc"];
 }
 
diff --git a/infer/tests/codetoanalyze/objc/performance/cost-issues.exp b/infer/tests/codetoanalyze/objc/performance/cost-issues.exp
index 8d710c4f7..9d24d2354 100644
--- a/infer/tests/codetoanalyze/objc/performance/cost-issues.exp
+++ b/infer/tests/codetoanalyze/objc/performance/cost-issues.exp
@@ -90,7 +90,7 @@ codetoanalyze/objc/performance/NSSet.m, nsset_init_with_array_linear, 6 + 3 ⋅
 codetoanalyze/objc/performance/NSSet.m, nsset_init_with_set_constant, 5,  OnUIThread:false, []
 codetoanalyze/objc/performance/NSSet.m, nsset_iterate_linear, 5 + 8 ⋅ (set->elements.length.ub + 1),  OnUIThread:false, [{set->elements.length.ub + 1},Loop]
 codetoanalyze/objc/performance/NSSet.m, nsset_next_object_linear, 4 + 5 ⋅ (set->elements.length.ub + 1),  OnUIThread:false, [{set->elements.length.ub + 1},Loop]
-codetoanalyze/objc/performance/NSString.m, DummyClass.call_string_by_appending_string_constant_FP, ⊤,  OnUIThread:false, [Unbounded loop,Modeled call to NSString.stringByAppendingString:]
+codetoanalyze/objc/performance/NSString.m, DummyClass.call_string_by_appending_string_constant, 7,  OnUIThread:false, []
 codetoanalyze/objc/performance/NSString.m, DummyClass.dealloc, 0,  OnUIThread:false, []
 codetoanalyze/objc/performance/NSString.m, call_component_separated_by_char_constant, 44,  OnUIThread:false, []
 codetoanalyze/objc/performance/NSString.m, call_init_with_string_constant, 13,  OnUIThread:false, []
diff --git a/infer/tests/codetoanalyze/objc/performance/issues.exp b/infer/tests/codetoanalyze/objc/performance/issues.exp
index 7f07153e3..93b3487e1 100644
--- a/infer/tests/codetoanalyze/objc/performance/issues.exp
+++ b/infer/tests/codetoanalyze/objc/performance/issues.exp
@@ -11,7 +11,6 @@ codetoanalyze/objc/performance/NSMutableArray.m, nsmarray_set_linear, 2, INTEGER
 codetoanalyze/objc/performance/NSSet.m, nsset_enumerator_linear, 7, INTEGER_OVERFLOW_L5, no_bucket, ERROR, [<LHS trace>,Assignment,<RHS trace>,Assignment,Binary operation: ([0, +oo] + [1, set->elements.length.ub + 1]):signed64]
 codetoanalyze/objc/performance/NSSet.m, nsset_init_constant, 3, CONDITION_ALWAYS_FALSE, no_bucket, WARNING, [Here]
 codetoanalyze/objc/performance/NSSet.m, nsset_iterate_linear, 3, INTEGER_OVERFLOW_L5, no_bucket, ERROR, [<LHS trace>,Assignment,<RHS trace>,Assignment,Binary operation: ([0, +oo] + [1, set->elements.length.ub + 1]):signed64]
-codetoanalyze/objc/performance/NSString.m, DummyClass.call_string_by_appending_string_constant_FP, 0, INFINITE_EXECUTION_TIME, no_bucket, ERROR, [Unbounded loop,Modeled call to NSString.stringByAppendingString:]
 codetoanalyze/objc/performance/NSString.m, init_string_constant, 2, CONDITION_ALWAYS_FALSE, no_bucket, WARNING, [Here]
 codetoanalyze/objc/performance/NSString.m, replace_linear_FP, 0, INFINITE_EXECUTION_TIME, no_bucket, ERROR, [Unbounded loop,Loop]
 codetoanalyze/objc/performance/NSString.m, replace_linear_FP, 2, INTEGER_OVERFLOW_U5, no_bucket, ERROR, [<LHS trace>,Unknown value from: NSString.stringByReplacingOccurrencesOfString:withString:,Binary operation: ([0, +oo] + 1):signed32]