diff --git a/src/Report/Html/Renderer/File.php b/src/Report/Html/Renderer/File.php
index 8f2c929b1..cbabb6a8e 100644
--- a/src/Report/Html/Renderer/File.php
+++ b/src/Report/Html/Renderer/File.php
@@ -304,7 +304,11 @@ protected function renderSource(FileNode $node)
             $popoverTitle   = '';
 
             if (array_key_exists($i, $coverageData)) {
-                $numTests = count($coverageData[$i]);
+                if (is_array($coverageData[$i])) {
+                    $numTests = count($coverageData[$i]);
+                } else {
+                    $numTests = 0;
+                }
 
                 if ($coverageData[$i] === null) {
                     $trClass = ' class="warning"';