diff --git a/frontend/src/components/Map.tsx b/frontend/src/components/Map.tsx
index 739dcf5..c4f9e66 100644
--- a/frontend/src/components/Map.tsx
+++ b/frontend/src/components/Map.tsx
@@ -103,8 +103,8 @@ export function Map(props: MapProps) {
             .sort(function (a: number, b: number) { return a - b; });
 
         if (values.length > 0) {
-            const minIndex = Math.round(values.length * PERCENTILE_CONFIG.MIN_BOUND);
-            const maxIndex = Math.round(values.length * PERCENTILE_CONFIG.MAX_BOUND);
+            const minIndex = Math.min(Math.round(values.length * PERCENTILE_CONFIG.MIN_BOUND), values.length - 1);
+            const maxIndex = Math.min(Math.round(values.length * PERCENTILE_CONFIG.MAX_BOUND), values.length - 1);
             const min = values[minIndex];
             // Ensure max > min so color stops are strictly monotonic
             const max = Math.max(values[maxIndex], min + 1);