diff --git a/ObjectiveGit/Categories/NSError+Git.h b/ObjectiveGit/Categories/NSError+Git.h
index bfe453dc0..4f7532f62 100644
--- a/ObjectiveGit/Categories/NSError+Git.h
+++ b/ObjectiveGit/Categories/NSError+Git.h
@@ -29,8 +29,12 @@
 
 #import <Foundation/Foundation.h>
 
+/// The error domain used by Objective-Git
 extern NSString * const GTGitErrorDomain;
 
+/// Error userinfo keys
+extern NSString * const GTGitErrorOID;
+
 @interface NSError (Git)
 
 /// Describes the given libgit2 error code, using any message provided by
diff --git a/ObjectiveGit/Categories/NSError+Git.m b/ObjectiveGit/Categories/NSError+Git.m
index cbc31509b..e66d2fcb3 100644
--- a/ObjectiveGit/Categories/NSError+Git.m
+++ b/ObjectiveGit/Categories/NSError+Git.m
@@ -31,6 +31,7 @@
 #import "git2/errors.h"
 
 NSString * const GTGitErrorDomain = @"GTGitErrorDomain";
+NSString * const GTGitErrorOID = @"GTOID";
 
 @implementation NSError (Git)
 
diff --git a/ObjectiveGit/GTEnumerator.h b/ObjectiveGit/GTEnumerator.h
index d3d9d60c2..900d3e60a 100644
--- a/ObjectiveGit/GTEnumerator.h
+++ b/ObjectiveGit/GTEnumerator.h
@@ -117,6 +117,16 @@ NS_ASSUME_NONNULL_BEGIN
 /// Returns a (possibly empty) array of GTCommits, or nil if an error occurs.
 - (nullable NSArray<GTCommit *> *)allObjectsWithError:(NSError **)error;
 
+/// Get the next OID.
+///
+/// success - If not NULL, this will be set to whether getting the next object
+///           was successful. This will be YES if the receiver is exhausted, so
+///           it can be used to interpret the meaning of a nil return value.
+/// error   - If not NULL, set to any error that occurs during traversal.
+///
+/// Returns nil if an error occurs or the enumeration is done.
+- (nullable GTOID *)nextOIDWithSuccess:(nullable BOOL *)success error:(NSError **)error;
+
 /// Gets the next commit.
 ///
 /// success - If not NULL, this will be set to whether getting the next object
diff --git a/ObjectiveGit/GTEnumerator.m b/ObjectiveGit/GTEnumerator.m
index 673d7f8c6..4b45a59f8 100644
--- a/ObjectiveGit/GTEnumerator.m
+++ b/ObjectiveGit/GTEnumerator.m
@@ -145,16 +145,34 @@ - (void)resetWithOptions:(GTEnumeratorOptions)options {
 
 #pragma mark Enumerating
 
-- (GTCommit *)nextObjectWithSuccess:(BOOL *)success error:(NSError **)error {
+- (GTOID *)nextOIDWithSuccess:(BOOL *)success error:(NSError **)error {
 	git_oid oid;
+
 	int gitError = git_revwalk_next(&oid, self.walk);
 	if (gitError == GIT_ITEROVER) {
 		if (success != NULL) *success = YES;
 		return nil;
 	}
+	if (gitError != GIT_OK) {
+		if (success != NULL) *success = NO;
+		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Enumeration failed"];
+		return nil;
+	}
+
+	if (success != NULL) *success = YES;
+	return [GTOID oidWithGitOid:&oid];
+}
+
+- (GTCommit *)nextObjectWithSuccess:(BOOL *)success error:(NSError **)error {
+	GTOID *oid = [self nextOIDWithSuccess:success error:error];
+	if (oid == nil) {
+		// We don't care whether the iteration completed, or an error occurred,
+		// there's nothing to lookup.
+		return nil;
+	}
 	
 	// Ignore error if we can't lookup object and just return nil.
-	GTCommit *commit = [self.repository lookUpObjectByGitOid:&oid objectType:GTObjectTypeCommit error:error];
+	GTCommit *commit = [self.repository lookUpObjectByOID:oid objectType:GTObjectTypeCommit error:error];
 	if (success != NULL) *success = (commit != nil);
 	return commit;
 }
diff --git a/ObjectiveGit/GTRepository.m b/ObjectiveGit/GTRepository.m
index c2483ab57..fc1e22d98 100644
--- a/ObjectiveGit/GTRepository.m
+++ b/ObjectiveGit/GTRepository.m
@@ -290,7 +290,7 @@ - (id)lookUpObjectByGitOid:(const git_oid *)oid objectType:(GTObjectType)type er
 		if (error != NULL) {
 			char oid_str[GIT_OID_HEXSZ+1];
 			git_oid_tostr(oid_str, sizeof(oid_str), oid);
-			*error = [NSError git_errorFor:gitError description:@"Failed to lookup object %s in repository.", oid_str];
+			*error = [NSError git_errorFor:gitError description:@"Failed to lookup object" userInfo:@{GTGitErrorOID: [GTOID oidWithGitOid:oid]} failureReason:@"The object %s couldn't be found in the repository.", oid_str];
 		}
 		return nil;
 	}