diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ef94c683a8a..25d455b8f77 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -127,3 +127,5 @@ this][modified-comment].
 [git-aliases]: https://github.com/willnorris/dotfiles/blob/d640d010c23b1116bdb3d4dc12088ed26120d87d/git/.gitconfig#L13-L15
 [rebase-comment]: https://github.com/google/go-github/pull/277#issuecomment-183035491
 [modified-comment]: https://github.com/google/go-github/pull/280#issuecomment-184859046
+
+**When creating a release, don't forget to update the `Version` constant in `github.go`.** This is used to send the version in the `User-Agent` header to identify clients to the GitHub API.
diff --git a/github/github.go b/github/github.go
index 08b7db8e55b..fe346f5ab72 100644
--- a/github/github.go
+++ b/github/github.go
@@ -28,9 +28,11 @@ import (
 )
 
 const (
-	defaultBaseURL = "https://api.github.com/"
-	uploadBaseURL  = "https://uploads.github.com/"
-	userAgent      = "go-github"
+	Version = "45.2.0"
+
+	defaultBaseURL   = "https://api.github.com/"
+	defaultUserAgent = "go-github" + "/" + Version
+	uploadBaseURL    = "https://uploads.github.com/"
 
 	headerRateLimit     = "X-RateLimit-Limit"
 	headerRateRemaining = "X-RateLimit-Remaining"
@@ -301,7 +303,7 @@ func NewClient(httpClient *http.Client) *Client {
 	baseURL, _ := url.Parse(defaultBaseURL)
 	uploadURL, _ := url.Parse(uploadBaseURL)
 
-	c := &Client{client: httpClient, BaseURL: baseURL, UserAgent: userAgent, UploadURL: uploadURL}
+	c := &Client{client: httpClient, BaseURL: baseURL, UserAgent: defaultUserAgent, UploadURL: uploadURL}
 	c.common.client = c
 	c.Actions = (*ActionsService)(&c.common)
 	c.Activity = (*ActivityService)(&c.common)
diff --git a/github/github_test.go b/github/github_test.go
index 0a28ced93c6..3fa5b4412a4 100644
--- a/github/github_test.go
+++ b/github/github_test.go
@@ -248,7 +248,7 @@ func TestNewClient(t *testing.T) {
 	if got, want := c.BaseURL.String(), defaultBaseURL; got != want {
 		t.Errorf("NewClient BaseURL is %v, want %v", got, want)
 	}
-	if got, want := c.UserAgent, userAgent; got != want {
+	if got, want := c.UserAgent, defaultUserAgent; got != want {
 		t.Errorf("NewClient UserAgent is %v, want %v", got, want)
 	}
 
@@ -507,10 +507,16 @@ func TestNewRequest(t *testing.T) {
 		t.Errorf("NewRequest(%q) Body is %v, want %v", inBody, got, want)
 	}
 
+	userAgent := req.Header.Get("User-Agent")
+
 	// test that default user-agent is attached to the request
-	if got, want := req.Header.Get("User-Agent"), c.UserAgent; got != want {
+	if got, want := userAgent, c.UserAgent; got != want {
 		t.Errorf("NewRequest() User-Agent is %v, want %v", got, want)
 	}
+
+	if !strings.Contains(userAgent, Version) {
+		t.Errorf("NewRequest() User-Agent should contain %v, found %v", Version, userAgent)
+	}
 }
 
 func TestNewRequest_invalidJSON(t *testing.T) {