diff --git a/docker/client.go b/docker/client.go
index 2b3082f..e108d81 100644
--- a/docker/client.go
+++ b/docker/client.go
@@ -1,7 +1,9 @@
 package docker
 
 import (
+	"fmt"
 	"log"
+	"strings"
 
 	"github.com/samalba/dockerclient"
 )
@@ -66,6 +68,10 @@ func (client DockerClient) RefreshImage(c *Container) error {
 	imageName := containerInfo.Config.Image
 
 	if pullImages {
+		if !strings.Contains(imageName, ":") {
+			imageName = fmt.Sprintf("%s:latest", imageName)
+		}
+
 		log.Printf("Pulling %s for %s\n", imageName, c.Name())
 		if err := client.api.PullImage(imageName, nil); err != nil {
 			return err
diff --git a/docker/client_test.go b/docker/client_test.go
index 4b5775c..3274d9f 100644
--- a/docker/client_test.go
+++ b/docker/client_test.go
@@ -80,8 +80,8 @@ func TestRefreshImage_NotStaleSuccess(t *testing.T) {
 	newImageInfo := &dockerclient.ImageInfo{Id: "abc123"}
 
 	api := mockclient.NewMockClient()
-	api.On("PullImage", "bar", mock.Anything).Return(nil)
-	api.On("InspectImage", "bar").Return(newImageInfo, nil)
+	api.On("PullImage", "bar:latest", mock.Anything).Return(nil)
+	api.On("InspectImage", "bar:latest").Return(newImageInfo, nil)
 
 	client := DockerClient{api: api}
 	err := client.RefreshImage(c)
@@ -95,15 +95,15 @@ func TestRefreshImage_StaleSuccess(t *testing.T) {
 	c := &Container{
 		containerInfo: &dockerclient.ContainerInfo{
 			Name:   "foo",
-			Config: &dockerclient.ContainerConfig{Image: "bar"},
+			Config: &dockerclient.ContainerConfig{Image: "bar:1.0"},
 		},
 		imageInfo: &dockerclient.ImageInfo{Id: "abc123"},
 	}
 	newImageInfo := &dockerclient.ImageInfo{Id: "xyz789"}
 
 	api := mockclient.NewMockClient()
-	api.On("PullImage", "bar", mock.Anything).Return(nil)
-	api.On("InspectImage", "bar").Return(newImageInfo, nil)
+	api.On("PullImage", "bar:1.0", mock.Anything).Return(nil)
+	api.On("InspectImage", "bar:1.0").Return(newImageInfo, nil)
 
 	client := DockerClient{api: api}
 	err := client.RefreshImage(c)
@@ -117,13 +117,13 @@ func TestRefreshImage_PullImageError(t *testing.T) {
 	c := &Container{
 		containerInfo: &dockerclient.ContainerInfo{
 			Name:   "foo",
-			Config: &dockerclient.ContainerConfig{Image: "bar"},
+			Config: &dockerclient.ContainerConfig{Image: "bar:latest"},
 		},
 		imageInfo: &dockerclient.ImageInfo{Id: "abc123"},
 	}
 
 	api := mockclient.NewMockClient()
-	api.On("PullImage", "bar", mock.Anything).Return(errors.New("oops"))
+	api.On("PullImage", "bar:latest", mock.Anything).Return(errors.New("oops"))
 
 	client := DockerClient{api: api}
 	err := client.RefreshImage(c)
@@ -137,15 +137,15 @@ func TestRefreshImage_InspectImageError(t *testing.T) {
 	c := &Container{
 		containerInfo: &dockerclient.ContainerInfo{
 			Name:   "foo",
-			Config: &dockerclient.ContainerConfig{Image: "bar"},
+			Config: &dockerclient.ContainerConfig{Image: "bar:latest"},
 		},
 		imageInfo: &dockerclient.ImageInfo{Id: "abc123"},
 	}
 	newImageInfo := &dockerclient.ImageInfo{}
 
 	api := mockclient.NewMockClient()
-	api.On("PullImage", "bar", mock.Anything).Return(nil)
-	api.On("InspectImage", "bar").Return(newImageInfo, errors.New("uh-oh"))
+	api.On("PullImage", "bar:latest", mock.Anything).Return(nil)
+	api.On("InspectImage", "bar:latest").Return(newImageInfo, errors.New("uh-oh"))
 
 	client := DockerClient{api: api}
 	err := client.RefreshImage(c)