diff --git a/packages/istanbul-lib-report/lib/summarizer.js b/packages/istanbul-lib-report/lib/summarizer.js
index 0dded28a..79ddc658 100644
--- a/packages/istanbul-lib-report/lib/summarizer.js
+++ b/packages/istanbul-lib-report/lib/summarizer.js
@@ -232,7 +232,7 @@ function createNestedSummary(coverageMap) {
         root;
 
     if (topNodes.length === 0) {
-        return treeFor(new ReportNode([]));
+        return treeFor(new ReportNode(new Path([])));
     }
 
     if (topNodes.length === 1) {
diff --git a/packages/istanbul-lib-report/test/summarizer.test.js b/packages/istanbul-lib-report/test/summarizer.test.js
index 45bad93d..e2d30e64 100644
--- a/packages/istanbul-lib-report/test/summarizer.test.js
+++ b/packages/istanbul-lib-report/test/summarizer.test.js
@@ -321,6 +321,14 @@ describe('summarizer', function() {
             assert.deepEqual(nodes, ['g:']);
         });
 
+        it('handles getting root node name without crashing when empty coverage map', function() {
+            var map = coverage.createCoverageMap({}),
+                tree = fn(map),
+                root = tree.getRoot(),
+                rootNodeName = root.getRelativeName();
+            assert.equal(rootNodeName, '');
+        });
+
         it('supports a list of files at top-level', function() {
             var map = singleDirMap(),
                 tree = fn(map),