diff --git a/prometheus/histogram_test.go b/prometheus/histogram_test.go
index 079866b..ddbe575 100644
--- a/prometheus/histogram_test.go
+++ b/prometheus/histogram_test.go
@@ -500,23 +500,26 @@ func TestNativeHistogram(t *testing.T) {
 		{
 			name: "factor 4 results in schema -1",
 			observations: []float64{
+				0.0156251, 0.0625, // Bucket -2: (0.015625, 0.0625)
+				0.1, 0.25, // Bucket -1: (0.0625, 0.25]
 				0.5, 1, // Bucket 0: (0.25, 1]
 				1.5, 2, 3, 3.5, // Bucket 1: (1, 4]
 				5, 6, 7, // Bucket 2: (4, 16]
 				33.33, // Bucket 3: (16, 64]
 			},
 			factor: 4,
-			want:   `sample_count:10 sample_sum:62.83 schema:-1 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:0 length:4 > positive_delta:2 positive_delta:2 positive_delta:-1 positive_delta:-2 `,
+			want:   `sample_count:14 sample_sum:63.2581251 schema:-1 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:-2 length:6 > positive_delta:2 positive_delta:0 positive_delta:0 positive_delta:2 positive_delta:-1 positive_delta:-2 `,
 		},
 		{
 			name: "factor 17 results in schema -2",
 			observations: []float64{
+				0.0156251, 0.0625, 0.1, 0.25, // Bucket -1: (0.015625, 0.25]
 				0.5, 1, // Bucket 0: (0.0625, 1]
 				1.5, 2, 3, 3.5, 5, 6, 7, // Bucket 1: (1, 16]
 				33.33, // Bucket 2: (16, 256]
 			},
 			factor: 17,
-			want:   `sample_count:10 sample_sum:62.83 schema:-2 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:0 length:3 > positive_delta:2 positive_delta:5 positive_delta:-6 `,
+			want:   `sample_count:14 sample_sum:63.2581251 schema:-2 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:-1 length:4 > positive_delta:4 positive_delta:-2 positive_delta:5 positive_delta:-6 `,
 		},
 		{
 			name:         "negative buckets",