diff --git a/autoroll/go/repo_manager/android_repo_manager.go b/autoroll/go/repo_manager/android_repo_manager.go
index 434b694..0276531 100644
--- a/autoroll/go/repo_manager/android_repo_manager.go
+++ b/autoroll/go/repo_manager/android_repo_manager.go
@@ -178,7 +178,7 @@
 
 // getLastRollRev returns the commit hash of the last-completed DEPS roll.
 func (r *androidRepoManager) getLastRollRev() (string, error) {
-	output, err := exec.RunCwd(r.childRepo.Dir(), "git", "log", "--pretty=format:%H", "--no-merges", "-1", "--first-parent", fmt.Sprintf("refs/remotes/remote/%s", r.childBranch))
+	output, err := exec.RunCwd(r.childRepo.Dir(), "git", "merge-base", fmt.Sprintf("refs/remotes/remote/%s", r.childBranch), fmt.Sprintf("refs/remotes/goog/%s", r.parentBranch))
 	if err != nil {
 		return "", err
 	}
diff --git a/autoroll/go/repo_manager/android_repo_manager_test.go b/autoroll/go/repo_manager/android_repo_manager_test.go
index 6c63893..9775d81 100644
--- a/autoroll/go/repo_manager/android_repo_manager_test.go
+++ b/autoroll/go/repo_manager/android_repo_manager_test.go
@@ -35,22 +35,19 @@
 			return nil
 		}
 		if cmd.Name == "git" {
+			var output string
 			if cmd.Args[0] == "log" {
-				var output string
-				if cmd.Args[1] == "--pretty=format:%H" {
-					output = childCommits[1]
-				} else if cmd.Args[1] == "--format=format:%H%x20%ci" {
+				if cmd.Args[1] == "--format=format:%H%x20%ci" {
 					output = fmt.Sprintf("%s 2017-03-29 18:29:22 +0000\n%s 2017-03-29 18:29:22 +0000", childCommits[0], childCommits[1])
 				}
-				n, err := cmd.CombinedOutput.Write([]byte(output))
-				assert.NoError(t, err)
-				assert.Equal(t, len(output), n)
 			} else if cmd.Args[0] == "ls-remote" {
-				childHead := childCommits[0]
-				n, err := cmd.CombinedOutput.Write([]byte(childHead))
-				assert.NoError(t, err)
-				assert.Equal(t, len(childHead), n)
+				output = childCommits[0]
+			} else if cmd.Args[0] == "merge-base" {
+				output = childCommits[1]
 			}
+			n, err := cmd.CombinedOutput.Write([]byte(output))
+			assert.NoError(t, err)
+			assert.Equal(t, len(output), n)
 		}
 		return nil
 	})