diff --git a/index.js b/index.js
index babd093..d7f050d 100644
--- a/index.js
+++ b/index.js
@@ -91,7 +91,7 @@ function diffContents(contents1, contents2, appendFn) {
 
     processContents(subSet1, subSet2, appendFn);
 
-    if (contents1[0] || contents2[0])
+    if (contents1[0] !== undefined || contents2[0] !== undefined)
         diffContents(contents1, contents2, appendFn);
 }
 
@@ -133,4 +133,4 @@ function processContents(contents1, contents2, appendFn) {
 
         if (result) appendFn(result);
     }
-}
\ No newline at end of file
+}