diff --git a/common/retry/retry.go b/common/retry/retry.go
index 34d2ba609..4233b2158 100644
--- a/common/retry/retry.go
+++ b/common/retry/retry.go
@@ -6,10 +6,12 @@ import (
 )
 
 var (
-	RetryFailed = errors.New("All retry attempts failed.")
+	errorRetryFailed = errors.New("All retry attempts failed.")
 )
 
+// Strategy is a way to retry on a specific function.
 type Strategy interface {
+  // On performs a retry on a specific function, until it doesn't return any error.
 	On(func() error) error
 }
 
@@ -17,6 +19,7 @@ type retryer struct {
 	NextDelay func(int) int
 }
 
+// On implements Strategy.On.
 func (r *retryer) On(method func() error) error {
 	attempt := 0
 	for {
@@ -26,13 +29,14 @@ func (r *retryer) On(method func() error) error {
 		}
 		delay := r.NextDelay(attempt)
 		if delay < 0 {
-			return RetryFailed
+			return errorRetryFailed
 		}
 		<-time.After(time.Duration(delay) * time.Millisecond)
 		attempt++
 	}
 }
 
+// Timed returns a retry strategy with fixed interval.
 func Timed(attempts int, delay int) Strategy {
 	return &retryer{
 		NextDelay: func(attempt int) int {
diff --git a/common/retry/retry_test.go b/common/retry/retry_test.go
index ed8249736..1c0be1a9a 100644
--- a/common/retry/retry_test.go
+++ b/common/retry/retry_test.go
@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	TestError = errors.New("This is a fake error.")
+	errorTestOnly = errors.New("This is a fake error.")
 )
 
 func TestNoRetry(t *testing.T) {
@@ -33,7 +33,7 @@ func TestRetryOnce(t *testing.T) {
 	err := Timed(10, 1000).On(func() error {
 		if called == 0 {
 			called++
-			return TestError
+			return errorTestOnly
 		}
 		return nil
 	})
@@ -51,7 +51,7 @@ func TestRetryMultiple(t *testing.T) {
 	err := Timed(10, 1000).On(func() error {
 		if called < 5 {
 			called++
-			return TestError
+			return errorTestOnly
 		}
 		return nil
 	})
@@ -69,12 +69,12 @@ func TestRetryExhausted(t *testing.T) {
 	err := Timed(2, 1000).On(func() error {
 		if called < 5 {
 			called++
-			return TestError
+			return errorTestOnly
 		}
 		return nil
 	})
 	duration := time.Since(startTime)
 
-	assert.Error(err).Equals(RetryFailed)
+	assert.Error(err).Equals(errorRetryFailed)
 	assert.Int64(int64(duration / time.Millisecond)).AtLeast(1900)
 }