diff --git a/ana/predictor.go b/ana/predictor.go
index 3c81f99..5f66e71 100644
--- a/ana/predictor.go
+++ b/ana/predictor.go
@@ -20,6 +20,8 @@ func NewInterestPredictor(namePattern string, currencyPattern string, apy float6
 			result[k] = maps.Clone(v)
 		}
 
+		monthsPassed := float64(delta) / float64(time.Hour*24.0*365.0/12.0)
+		scalar := math.Pow(1.0+apy/12.0, monthsPassed)
 		for name := range result {
 			if !nameMatcher.MatchString(name) {
 				continue
@@ -28,8 +30,7 @@ func NewInterestPredictor(namePattern string, currencyPattern string, apy float6
 				if !currencyMatcher.MatchString(string(currency)) {
 					continue
 				}
-				percentOfYearPassed := float64(delta) / float64(time.Hour*365)
-				result[name][currency] *= math.Pow(1.0+apy/12.0, percentOfYearPassed)
+				result[name][currency] *= scalar
 			}
 		}
 		return result
diff --git a/ana/predictor_test.go b/ana/predictor_test.go
index 2769735..37d51a0 100644
--- a/ana/predictor_test.go
+++ b/ana/predictor_test.go
@@ -8,7 +8,7 @@ import (
 )
 
 func TestNewInterestPredictor(t *testing.T) {
-	name := "x"
+	acc := "x"
 	curr := ledger.USD
 	cases := map[string]struct {
 		apy   float64
@@ -18,22 +18,22 @@ func TestNewInterestPredictor(t *testing.T) {
 	}{
 		"zero": {
 			apy:   0,
-			given: ledger.Balances{name: ledger.Balance{curr: 100}},
+			given: ledger.Balances{acc: ledger.Balance{curr: 100}},
 			delta: time.Hour * 24 * 365,
-			want:  ledger.Balances{name: ledger.Balance{curr: 100}},
+			want:  ledger.Balances{acc: ledger.Balance{curr: 100}},
 		},
-		"100%": {
-			apy:   1,
-			given: ledger.Balances{name: ledger.Balance{curr: 100}},
+		"50%": {
+			apy:   .5,
+			given: ledger.Balances{acc: ledger.Balance{curr: 100}},
 			delta: time.Hour * 24 * 365,
-			want:  ledger.Balances{name: ledger.Balance{curr: 200}},
+			want:  ledger.Balances{acc: ledger.Balance{curr: 163.21}},
 		},
 	}
 
 	for name, d := range cases {
 		c := d
 		t.Run(name, func(t *testing.T) {
-			predictor := NewInterestPredictor(name, string(curr), c.apy)
+			predictor := NewInterestPredictor(acc, string(curr), c.apy)
 			got := predictor(c.given, c.delta)
 			if got.Debug() != c.want.Debug() {
 				t.Errorf("want\n\t%+v, got\n\t%+v", c.want, got)