diff --git a/src/game/formulas/formulas.ts b/src/game/formulas/formulas.ts
index 9f6ad5a..cdc4b0e 100644
--- a/src/game/formulas/formulas.ts
+++ b/src/game/formulas/formulas.ts
@@ -1426,14 +1426,14 @@ export function calculateMaxAffordable(
                 summedPurchases = 0;
             }
         }
-        if (summedPurchases > 0) {
+        if (summedPurchases > 0 && Decimal.lt(calculateCost(formula, affordable, true, 0), 1e308)) {
             affordable = affordable.sub(summedPurchases).clampMin(0);
             let summedCost = calculateCost(formula, affordable, true, 0);
             while (true) {
                 const nextCost = formula.evaluate(
                     affordable.add(unref(formula.innermostVariable) ?? 0)
                 );
-                if (Decimal.add(summedCost, nextCost).lt(resource.value)) {
+                if (Decimal.add(summedCost, nextCost).lte(resource.value)) {
                     affordable = affordable.add(1);
                     summedCost = Decimal.add(summedCost, nextCost);
                 } else {
diff --git a/tests/game/formulas.test.ts b/tests/game/formulas.test.ts
index 86ec8c4..69254cf 100644
--- a/tests/game/formulas.test.ts
+++ b/tests/game/formulas.test.ts
@@ -1174,6 +1174,24 @@ describe("Buy Max", () => {
             // Since we're summing all the purchases this should be equivalent
             expect(calculatedCost).compare_tolerance(actualCost);
         });
+        test("Handles summing purchases when making very few purchases", () => {
+            const purchases = ref(0);
+            const variable = Formula.variable(purchases);
+            const formula = variable.add(1);
+            const resource = createResource(ref(3));
+            const maxAffordable = calculateMaxAffordable(formula, resource, true);
+            expect(maxAffordable.value).compare_tolerance(2);
+
+            const actualCost = new Array(2)
+                .fill(null)
+                .reduce(
+                    (acc, _, i) => acc.add(formula.evaluate(i + purchases.value)),
+                    new Decimal(0)
+                );
+            const calculatedCost = calculateCost(formula, maxAffordable.value, true);
+            // Since we're summing all the purchases this should be equivalent
+            expect(calculatedCost).compare_tolerance(actualCost);
+        });
         test("Handles summing purchases when over e308 purchases", () => {
             resource.value = "1ee308";
             const purchases = ref(0);