diff --git a/zipkin/propagation.go b/zipkin/propagation.go
index 722b0875..cd7d52d7 100644
--- a/zipkin/propagation.go
+++ b/zipkin/propagation.go
@@ -61,9 +61,9 @@ func (p Propagator) Inject(
 
 	textMapWriter.Set("x-b3-traceid", sc.TraceID().String())
 	if sc.ParentID() != 0 {
-		textMapWriter.Set("x-b3-parentspanid", strconv.FormatUint(uint64(sc.ParentID()), 16))
+		textMapWriter.Set("x-b3-parentspanid", sc.ParentID().String())
 	}
-	textMapWriter.Set("x-b3-spanid", strconv.FormatUint(uint64(sc.SpanID()), 16))
+	textMapWriter.Set("x-b3-spanid", sc.SpanID().String())
 	if sc.IsSampled() {
 		textMapWriter.Set("x-b3-sampled", "1")
 	} else {
diff --git a/zipkin/propagation_test.go b/zipkin/propagation_test.go
index d7c5c6f6..95771a7e 100644
--- a/zipkin/propagation_test.go
+++ b/zipkin/propagation_test.go
@@ -33,31 +33,31 @@ var (
 var (
 	rootSampledHeader = opentracing.TextMapCarrier{
 		"x-b3-traceid": "0000000000000001",
-		"x-b3-spanid":  "2",
+		"x-b3-spanid":  "0000000000000002",
 		"x-b3-sampled": "1",
 		"baggage-foo":  "bar",
 	}
 	nonRootSampledHeader = opentracing.TextMapCarrier{
 		"x-b3-traceid":      "0000000000000001",
-		"x-b3-spanid":       "2",
-		"x-b3-parentspanid": "1",
+		"x-b3-spanid":       "0000000000000002",
+		"x-b3-parentspanid": "0000000000000001",
 		"x-b3-sampled":      "1",
 	}
 	nonRootNonSampledHeader = opentracing.TextMapCarrier{
 		"x-b3-traceid":      "0000000000000001",
-		"x-b3-spanid":       "2",
-		"x-b3-parentspanid": "1",
+		"x-b3-spanid":       "0000000000000002",
+		"x-b3-parentspanid": "0000000000000001",
 		"x-b3-sampled":      "0",
 	}
 	rootSampledBooleanHeader = opentracing.TextMapCarrier{
 		"x-b3-traceid": "0000000000000001",
-		"x-b3-spanid":  "2",
+		"x-b3-spanid":  "0000000000000002",
 		"x-b3-sampled": "true",
 		"baggage-foo":  "bar",
 	}
 	nonRootSampledBooleanHeader = opentracing.TextMapCarrier{
 		"x-b3-traceid":      "0000000000000001",
-		"x-b3-spanid":       "2",
+		"x-b3-spanid":       "0000000000000002",
 		"x-b3-parentspanid": "1",
 		"x-b3-sampled":      "true",
 	}
@@ -69,12 +69,12 @@ var (
 	}
 	sampled128bitTraceID = opentracing.TextMapCarrier{
 		"x-b3-traceid": "463ac35c9f6413ad48485a3953bb6124",
-		"x-b3-spanid":  "2",
+		"x-b3-spanid":  "0000000000000002",
 		"x-b3-sampled": "1",
 	}
 	invalidTraceID = opentracing.TextMapCarrier{
 		"x-b3-traceid": "00000000000000000000000000000000",
-		"x-b3-spanid":  "2",
+		"x-b3-spanid":  "0000000000000002",
 		"x-b3-sampled": "1",
 	}
 )
@@ -157,7 +157,7 @@ func TestCustomBaggagePrefix(t *testing.T) {
 	assert.Nil(t, err)
 	m := opentracing.TextMapCarrier{
 		"x-b3-traceid": "0000000000000001",
-		"x-b3-spanid":  "2",
+		"x-b3-spanid":  "0000000000000002",
 		"x-b3-sampled": "1",
 		"emoji:)foo":   "bar",
 	}