diff --git a/modules/git/diff.go b/modules/git/diff.go
index 6faad1c3c0..5da53568e5 100644
--- a/modules/git/diff.go
+++ b/modules/git/diff.go
@@ -47,7 +47,7 @@ func GetRawDiffForFile(repoPath, startCommit, endCommit string, diffType RawDiff
 func GetRepoRawDiffForFile(repo *Repository, startCommit, endCommit string, diffType RawDiffType, file string, writer io.Writer) error {
 	commit, err := repo.GetCommit(endCommit)
 	if err != nil {
-		return fmt.Errorf("GetCommit: %v", err)
+		return err
 	}
 	fileArgs := make([]string, 0)
 	if len(file) > 0 {
diff --git a/routers/repo/commit.go b/routers/repo/commit.go
index d9547cc51d..11329727e4 100644
--- a/routers/repo/commit.go
+++ b/routers/repo/commit.go
@@ -6,6 +6,7 @@
 package repo
 
 import (
+	"errors"
 	"path"
 	"strings"
 
@@ -341,6 +342,11 @@ func RawDiff(ctx *context.Context) {
 		git.RawDiffType(ctx.Params(":ext")),
 		ctx.Resp,
 	); err != nil {
+		if git.IsErrNotExist(err) {
+			ctx.NotFound("GetRawDiff",
+				errors.New("commit "+ctx.Params(":sha")+" does not exist."))
+			return
+		}
 		ctx.ServerError("GetRawDiff", err)
 		return
 	}