diff --git a/src/tree/tree_model.cc b/src/tree/tree_model.cc
index a8af7c51ec3b..94e3bc97abb2 100644
--- a/src/tree/tree_model.cc
+++ b/src/tree/tree_model.cc
@@ -315,7 +315,7 @@ class TextGenerator : public TreeGenerator {
     auto cats = GetSplitCategories(tree, nid);
     std::string cats_str = PrintCatsAsSet(cats);
     static std::string const kNodeTemplate =
-        "{tabs}{nid}:[{fname}={cond}] yes={right},no={left},missing={missing}";
+        "{tabs}{nid}:[{fname}:{cond}] yes={right},no={left},missing={missing}";
     std::string const result =
         SplitNodeImpl(tree, nid, kNodeTemplate, cats_str, depth);
     return result;
@@ -662,7 +662,7 @@ class GraphvizGenerator : public TreeGenerator {
 
   std::string Categorical(RegTree const& tree, int32_t nid, uint32_t) const override {
     static std::string const kLabelTemplate =
-        "    {nid} [ label=\"{fname}={cond}\" {params}]\n";
+        "    {nid} [ label=\"{fname}:{cond}\" {params}]\n";
     auto cats = GetSplitCategories(tree, nid);
     auto cats_str = PrintCatsAsSet(cats);
     auto split = tree[nid].SplitIndex();