diff --git a/psyneulink/core/components/functions/nonstateful/optimizationfunctions.py b/psyneulink/core/components/functions/nonstateful/optimizationfunctions.py
index 262f4bb628b..5ff6359225e 100644
--- a/psyneulink/core/components/functions/nonstateful/optimizationfunctions.py
+++ b/psyneulink/core/components/functions/nonstateful/optimizationfunctions.py
@@ -2103,22 +2103,25 @@ def _function(self,
                 # select_min params are:
                 # params, state, min_sample_ptr, sample_ptr, min_value_ptr, value_ptr, opt_count_ptr, count
                 min_tags = frozenset({"select_min", "evaluate_type_objective"})
-                bin_func = pnlvm.LLVMBinaryFunction.from_obj(self, tags=min_tags)
+                bin_func = pnlvm.LLVMBinaryFunction.from_obj(self, tags=min_tags, numpy_args=(2, 4, 6))
 
                 ct_param = bin_func.byref_arg_types[0](*self._get_param_initializer(context))
                 ct_state = bin_func.byref_arg_types[1](*self._get_state_initializer(context))
-                ct_opt_sample = bin_func.byref_arg_types[2](float("NaN"))
-                ct_alloc = None # NULL for samples
-                ct_opt_value = bin_func.byref_arg_types[4]()
-                ct_opt_count = bin_func.byref_arg_types[6](0)
-                ct_start = bin_func.c_func.argtypes[7](0)
-                ct_stop = bin_func.c_func.argtypes[8](num_values)
-
-                bin_func(ct_param, ct_state, ct_opt_sample, ct_alloc, ct_opt_value,
-                         ct_values, ct_opt_count, ct_start, ct_stop)
-
-                optimal_value = ct_opt_value.value
-                optimal_sample = np.ctypeslib.as_array(ct_opt_sample)
+                optimal_sample = bin_func.np_buffer_for_arg(2)
+                optimal_value = bin_func.np_buffer_for_arg(4)
+                number_of_optimal_values = bin_func.np_buffer_for_arg(6, fill_value=0)
+
+                bin_func(ct_param,
+                         ct_state,
+                         optimal_sample,
+                         None,                                     # samples. NULL, it's generated by the function.
+                         optimal_value,
+                         ct_values,
+                         number_of_optimal_values,
+                         bin_func.c_func.argtypes[7](0),           # start
+                         bin_func.c_func.argtypes[8](num_values))  # stop
+
+                # Convert outputs to Numpy/Python
                 all_values = np.ctypeslib.as_array(ct_values)
 
             # Python version
diff --git a/psyneulink/core/llvm/__init__.py b/psyneulink/core/llvm/__init__.py
index 4b20e49aa97..568ef7ec910 100644
--- a/psyneulink/core/llvm/__init__.py
+++ b/psyneulink/core/llvm/__init__.py
@@ -226,13 +226,13 @@ def cuda_wrap_call(self, *args, **kwargs):
         wrap_args = (jit_engine.pycuda.driver.InOut(a) if isinstance(a, np.ndarray) else a for a in args)
         self.cuda_call(*wrap_args, **kwargs)
 
-    def np_buffer_for_arg(self, arg_num, *, extra_dimensions=()):
+    def np_buffer_for_arg(self, arg_num, *, extra_dimensions=(), fill_value=np.nan):
 
         out_base = self.np_params[arg_num].base
         out_shape = extra_dimensions + self.np_params[arg_num].shape
 
         # fill the buffer with NaN poison
-        return np.full(out_shape, np.nan, dtype=out_base)
+        return np.full(out_shape, fill_value, dtype=out_base)
 
     @staticmethod
     @functools.lru_cache(maxsize=32)