diff --git a/src/metric/metric.cc b/src/metric/metric.cc
index db7753d68..0d73ee690 100644
--- a/src/metric/metric.cc
+++ b/src/metric/metric.cc
@@ -15,13 +15,22 @@ namespace xgboost {
 Metric* Metric::Create(const std::string& name, LearnerTrainParam const* tparam) {
   std::string buf = name;
   std::string prefix = name;
+  const char* param;
   auto pos = buf.find('@');
   if (pos == std::string::npos) {
-    auto *e = ::dmlc::Registry< ::xgboost::MetricReg>::Get()->Find(name);
+    if (!buf.empty() && buf.back() == '-') {
+      // Metrics of form "metric-"
+      prefix = buf.substr(0, buf.length() - 1);  // Chop off '-'
+      param = "-";
+    } else {
+      prefix = buf;
+      param = nullptr;
+    }
+    auto *e = ::dmlc::Registry< ::xgboost::MetricReg>::Get()->Find(prefix.c_str());
     if (e == nullptr) {
       LOG(FATAL) << "Unknown metric function " << name;
     }
-    auto p_metric = (e->body)(nullptr);
+    auto p_metric = (e->body)(param);
     p_metric->tparam_ = tparam;
     return p_metric;
   } else {
diff --git a/src/metric/rank_metric.cc b/src/metric/rank_metric.cc
index 6e4832109..bb1b053b7 100644
--- a/src/metric/rank_metric.cc
+++ b/src/metric/rank_metric.cc
@@ -285,10 +285,13 @@ struct EvalRankList : public Metric {
     minus_ = false;
     if (param != nullptr) {
       std::ostringstream os;
-      os << name << '@' << param;
-      name_ = os.str();
-      if (sscanf(param, "%u[-]?", &topn_) != 1) {
+      if (sscanf(param, "%u[-]?", &topn_) == 1) {
+        os << name << '@' << param;
+        name_ = os.str();
+      } else {
         topn_ = std::numeric_limits<unsigned>::max();
+        os << name << param;
+        name_ = os.str();
       }
       if (param[strlen(param) - 1] == '-') {
         minus_ = true;
diff --git a/tests/cpp/metric/test_rank_metric.cc b/tests/cpp/metric/test_rank_metric.cc
index 3aa8f0fa8..ef1d1377f 100644
--- a/tests/cpp/metric/test_rank_metric.cc
+++ b/tests/cpp/metric/test_rank_metric.cc
@@ -113,7 +113,18 @@ TEST(Metric, NDCG) {
 
   delete metric;
   metric = xgboost::Metric::Create("ndcg@-", &tparam);
-  ASSERT_STREQ(metric->Name(), "ndcg@-");
+  ASSERT_STREQ(metric->Name(), "ndcg-");
+  EXPECT_NEAR(GetMetricEval(metric,
+                            xgboost::HostDeviceVector<xgboost::bst_float>{},
+                            {}), 0, 1e-10);
+  EXPECT_NEAR(GetMetricEval(metric, {0, 1}, {0, 1}), 1, 1e-10);
+  EXPECT_NEAR(GetMetricEval(metric,
+                            {0.1f, 0.9f, 0.1f, 0.9f},
+                            {  0,   0,   1,   1}),
+              0.6509f, 0.001f);
+  delete metric;
+  metric = xgboost::Metric::Create("ndcg-", &tparam);
+  ASSERT_STREQ(metric->Name(), "ndcg-");
   EXPECT_NEAR(GetMetricEval(metric,
                             xgboost::HostDeviceVector<xgboost::bst_float>{},
                             {}), 0, 1e-10);
@@ -150,7 +161,14 @@ TEST(Metric, MAP) {
 
   delete metric;
   metric = xgboost::Metric::Create("map@-", &tparam);
-  ASSERT_STREQ(metric->Name(), "map@-");
+  ASSERT_STREQ(metric->Name(), "map-");
+  EXPECT_NEAR(GetMetricEval(metric,
+                            xgboost::HostDeviceVector<xgboost::bst_float>{},
+                            {}), 0, 1e-10);
+
+  delete metric;
+  metric = xgboost::Metric::Create("map-", &tparam);
+  ASSERT_STREQ(metric->Name(), "map-");
   EXPECT_NEAR(GetMetricEval(metric,
                             xgboost::HostDeviceVector<xgboost::bst_float>{},
                             {}), 0, 1e-10);