diff --git a/model/samplevalue.go b/model/samplevalue.go
index 72445cc..eb8dd3a 100644
--- a/model/samplevalue.go
+++ b/model/samplevalue.go
@@ -15,6 +15,7 @@ package model
 
 import (
 	"fmt"
+	"strconv"
 )
 
 // A SampleValue is a representation of a value for a given sample at a given
@@ -28,9 +29,9 @@ func (v SampleValue) Equal(o SampleValue) bool {
 
 // MarshalJSON implements json.Marshaler.
 func (v SampleValue) MarshalJSON() ([]byte, error) {
-	return []byte(fmt.Sprintf(`"%f"`, v)), nil
+	return []byte(fmt.Sprintf(`"%s"`, v)), nil
 }
 
 func (v SampleValue) String() string {
-	return fmt.Sprint(float64(v))
+	return strconv.FormatFloat(float64(v), 'f', -1, 64)
 }
diff --git a/model/timestamp.go b/model/timestamp.go
index e0c6dd4..4c8fcf8 100644
--- a/model/timestamp.go
+++ b/model/timestamp.go
@@ -14,7 +14,8 @@
 package model
 
 import (
-	"fmt"
+	"strconv"
+
 	native_time "time"
 )
 
@@ -81,7 +82,7 @@ func (t Timestamp) UnixNano() int64 {
 
 // String returns a string representation of the timestamp.
 func (t Timestamp) String() string {
-	return fmt.Sprintf("%f", float64(t)/float64(second))
+	return strconv.FormatFloat(float64(t)/float64(second), 'f', -1, 64)
 }
 
 func (t Timestamp) MarshalJSON() ([]byte, error) {