diff --git a/cmd/frontend/graphqlbackend/git_blob.go b/cmd/frontend/graphqlbackend/git_blob.go
index fef57d93535..fa1b0d49c36 100644
--- a/cmd/frontend/graphqlbackend/git_blob.go
+++ b/cmd/frontend/graphqlbackend/git_blob.go
@@ -10,8 +10,8 @@ import (
 )
 
 type GitTreeEntryBlameArgs struct {
-	StartLine        int32
-	EndLine          int32
+	StartLine        *int32
+	EndLine          *int32
 	IgnoreWhitespace bool
 }
 
@@ -19,10 +19,17 @@ func (r *GitTreeEntryResolver) Blame(ctx context.Context, args *GitTreeEntryBlam
 	opts := &gitserver.BlameOptions{
 		NewestCommit:     api.CommitID(r.commit.OID()),
 		IgnoreWhitespace: args.IgnoreWhitespace,
-		Range: &gitserver.BlameRange{
-			StartLine: int(args.StartLine),
-			EndLine:   int(args.EndLine),
-		},
+	}
+
+	if (args.StartLine == nil) != (args.EndLine == nil) {
+		return nil, errors.New("both startLine and endLine must be specified or neither")
+	}
+
+	if args.StartLine != nil && args.EndLine != nil {
+		opts.Range = &gitserver.BlameRange{
+			StartLine: int(*args.StartLine),
+			EndLine:   int(*args.EndLine),
+		}
 	}
 
 	hr, err := r.gitserverClient.StreamBlameFile(ctx, r.commit.repoResolver.RepoName(), r.Path(), opts)
diff --git a/cmd/frontend/graphqlbackend/schema.graphql b/cmd/frontend/graphqlbackend/schema.graphql
index 373d38b7c21..996863be585 100755
--- a/cmd/frontend/graphqlbackend/schema.graphql
+++ b/cmd/frontend/graphqlbackend/schema.graphql
@@ -6063,7 +6063,7 @@ type GitBlob implements TreeEntry & File2 {
     """
     Blame the blob.
     """
-    blame(startLine: Int!, endLine: Int!, ignoreWhitespace: Boolean = false): [Hunk!]!
+    blame(startLine: Int, endLine: Int, ignoreWhitespace: Boolean = false): [Hunk!]!
     """
     Highlight the blob contents.
     """