diff --git a/githubissues/main.go b/githubissues/main.go
index 18752940..9e760790 100644
--- a/githubissues/main.go
+++ b/githubissues/main.go
@@ -98,7 +98,12 @@ func (g *githubissuesNotifier) SendNotification(ctx context.Context, build *cbpb
 		return nil
 	}
 
-	webhookURL := fmt.Sprintf("%s/%s/issues", githubApiEndpoint, g.githubRepo)
+	repo := GetGithubRepo(build)
+	if repo == "" {
+		log.Warningf("could not determine GitHub repository from build, skipping notification")
+		return nil
+	}
+	webhookURL := fmt.Sprintf("%s/%s/issues", githubApiEndpoint, repo)
 
 	log.Infof("sending GitHub Issue webhook for Build %q (status: %q) to url %q", build.Id, build.Status, webhookURL)
 
@@ -148,3 +153,12 @@ func (g *githubissuesNotifier) SendNotification(ctx context.Context, build *cbpb
 	log.V(2).Infoln("send HTTP request successfully")
 	return nil
 }
+
+func GetGithubRepo(build *cbpb.Build) string {
+	if build.Substitutions != nil && build.Substitutions["REPO_FULL_NAME"] != "" {
+		// return repo full name if it's available
+		// e.g. "GoogleCloudPlatform/cloud-build-notifiers"
+		return build.Substitutions["REPO_FULL_NAME"]
+	}
+	return ""
+}
diff --git a/githubissues/main_test.go b/githubissues/main_test.go
index 28927541..8d3577c9 100644
--- a/githubissues/main_test.go
+++ b/githubissues/main_test.go
@@ -161,3 +161,33 @@ func TestConfigs(t *testing.T) {
 		})
 	}
 }
+
+func TestGetGithubRepo(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		build    *cbpb.Build
+		expected string
+	}{{
+		name: "REPO_FULL_NAME is set",
+		// test GetGithubRepo method
+		build: &cbpb.Build{
+			Substitutions: map[string]string{"REPO_FULL_NAME": "somename/somerepo"},
+		},
+		expected: "somename/somerepo",
+	}, {
+		name: "REPO_FULL_NAME is not set",
+		// test GetGithubRepo method
+		build: &cbpb.Build{
+			Substitutions: map[string]string{},
+		},
+		expected: "",
+	},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := GetGithubRepo(tc.build)
+			if actual != tc.expected {
+				t.Errorf("expected %q, got %q", tc.expected, actual)
+			}
+		})
+	}
+}