diff --git a/src/Report/Html/Renderer/File.php b/src/Report/Html/Renderer/File.php
index 5461c9e76..063a68eb1 100644
--- a/src/Report/Html/Renderer/File.php
+++ b/src/Report/Html/Renderer/File.php
@@ -304,7 +304,7 @@ protected function renderSource(FileNode $node)
             $popoverTitle   = '';
 
             if (array_key_exists($i, $coverageData)) {
-                $numTests = count($coverageData[$i]);
+                $numTests = is_array($coverageData[$i]) ? count($coverageData[$i]) : 0;
 
                 if ($coverageData[$i] === null) {
                     $trClass = ' class="warning"';