diff --git a/go/squiggle.go b/go/squiggle.go
index 8b46c786..46903415 100644
--- a/go/squiggle.go
+++ b/go/squiggle.go
@@ -58,23 +58,24 @@ func sample_mixture(fs []func64, weights []float64) float64 {
 	}
 
 	var total float64 = 0
+	var cumsummed_normalized_weights = append([]float64(nil), weights...)
 	for i, weight := range weights {
 		total += weight / sum_weights
-		weights[i] = total
+		cumsummed_normalized_weights[i] = total
 	}
 
 	var result float64
 	var flag int = 0
 	var p float64 = r.Float64()
 
-	for i, weight := range weights {
-		if p < weight {
+	for i, cnw := range cumsummed_normalized_weights {
+		if p < cnw {
 			result = fs[i]()
 			flag = 1
 			break
 		}
 	}
-	fmt.Println(weights)
+	fmt.Println(cumsummed_normalized_weights)
 
 	if flag == 0 {
 		result = fs[len(fs)-1]()
@@ -98,7 +99,7 @@ func main() {
 	ws := [4](float64){1 - p_c, p_c / 2, p_c / 4, p_c / 4}
 	fmt.Println("weights #1", ws)
 
-	var n_samples int = 20
+	var n_samples int = 1_000_000
 	var avg float64 = 0
 	for i := 0; i < n_samples; i++ {
 		x := sample_mixture(fs[0:], ws[0:])