diff --git a/e2e/cypress/integration/tests/actions.spec.js b/e2e/cypress/integration/tests/actions.spec.js
index 89d4a788..5df7a558 100644
--- a/e2e/cypress/integration/tests/actions.spec.js
+++ b/e2e/cypress/integration/tests/actions.spec.js
@@ -10,7 +10,8 @@ context('Actions', () => {
 
     // This gets the "first" input from the sidebar. From clicking step up,
     // the Regional Population should increase from default 4119405 to 4219405.
+    // Updated to 3600000
     cy.get('input.st-al').eq(0)
-      .should('has.value', '4119406')
+      .should('has.value', '3600000')
   })
 });
diff --git a/src/penn_chime/models.py b/src/penn_chime/models.py
index 19d1fe1e..457f4df2 100644
--- a/src/penn_chime/models.py
+++ b/src/penn_chime/models.py
@@ -182,7 +182,10 @@ def get_loss(self) -> float:
 
 
 def get_argmin_ds(census_df: pd.DataFrame, current_hospitalized: float) -> float:
-    losses_df = (census_df.hospitalized - current_hospitalized) ** 2.0
+    # By design, this forbids choosing a day after the peak
+    # If that's a problem, see #381
+    peak_day = census_df.hospitalized.argmax()
+    losses_df = (census_df.hospitalized[:peak_day] - current_hospitalized) ** 2.0
     return losses_df.argmin()