diff --git a/src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java b/src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java
index 9436933c8702f99c31db19a8aa3aa81073346ffe..f90179cef535ab1a8255d22b8f96ea306741c4da 100644
--- a/src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java
+++ b/src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java
@@ -16,6 +16,8 @@ import java.util.stream.Collectors;
 
 import de.uni_passau.fim.seibt.gitwrapper.process.ProcessExecutor.ExecRes;
 
+import static de.uni_passau.fim.seibt.gitwrapper.repo.GitWrapper.EXIT_SUCCESS;
+
 /**
  * A git {@link Repository}.
  */
@@ -94,7 +96,7 @@ public class Repository {
         Optional<ExecRes> mergeBase = git.exec(dir, "merge-base", a.getId(), b.getId());
         Function<ExecRes, Commit> toCommit = res -> {
 
-            if (res.output.startsWith(FAILURE_PREFIX)) {
+            if (res.exitCode != EXIT_SUCCESS || res.output.startsWith(FAILURE_PREFIX)) {
                 return null;
             }