diff --git a/oracle/callgraph.go b/oracle/callgraph.go
index 53e559b85fe..91b05d2766c 100644
--- a/oracle/callgraph.go
+++ b/oracle/callgraph.go
@@ -127,6 +127,7 @@ func (r *callgraphResult) toSerial(res *serial.Result, fset *token.FileSet) {
 		for callee := range call.CalleesOf(n) {
 			j.Children = append(j.Children, numbering[callee])
 		}
+		sort.Ints(j.Children)
 	}
 	res.Callgraph = cg
 }
diff --git a/oracle/oracle_test.go b/oracle/oracle_test.go
index 2ab26973f99..85a3ae4b29f 100644
--- a/oracle/oracle_test.go
+++ b/oracle/oracle_test.go
@@ -211,8 +211,7 @@ func TestOracle(t *testing.T) {
 		"testdata/src/main/what.go",
 		// JSON:
 		// TODO(adonovan): most of these are very similar; combine them.
-		// TODO(adonovan): enable this test once it works again.
-		//"testdata/src/main/callgraph-json.go",
+		"testdata/src/main/callgraph-json.go",
 		"testdata/src/main/calls-json.go",
 		"testdata/src/main/peers-json.go",
 		"testdata/src/main/describe-json.go",