diff --git a/timemachine/fe/rbfe.py b/timemachine/fe/rbfe.py
index f772a4ded7..5b806b3bc6 100644
--- a/timemachine/fe/rbfe.py
+++ b/timemachine/fe/rbfe.py
@@ -698,7 +698,7 @@ def run_vacuum(
         md_params = replace(md_params, local_steps=0)
         warnings.warn("Vacuum simulations don't support local steps, will use all global steps")
     # min_cutoff defaults to None since there is no environment to prevent conformational changes in the ligand
-    return estimate_relative_free_energy_bisection(
+    return estimate_relative_free_energy_bisection_hrex(
         mol_a,
         mol_b,
         core,
@@ -729,7 +729,7 @@ def run_solvent(
     solvent_sys, solvent_conf, solvent_box, solvent_top = builders.build_water_system(box_width, forcefield.water_ff)
     solvent_box += np.diag([0.1, 0.1, 0.1])  # remove any possible clashes, deboggle later
     solvent_host_config = HostConfig(solvent_sys, solvent_conf, solvent_box, solvent_conf.shape[0])
-    solvent_res = estimate_relative_free_energy_bisection(
+    solvent_res = estimate_relative_free_energy_bisection_hrex(
         mol_a,
         mol_b,
         core,
@@ -762,7 +762,7 @@ def run_complex(
     )
     complex_box += np.diag([0.1, 0.1, 0.1])  # remove any possible clashes, deboggle later
     complex_host_config = HostConfig(complex_sys, complex_conf, complex_box, nwa)
-    complex_res = estimate_relative_free_energy_bisection(
+    complex_res = estimate_relative_free_energy_bisection_hrex(
         mol_a,
         mol_b,
         core,