diff --git a/papaparse.js b/papaparse.js
index ad84d24..e955e4a 100644
--- a/papaparse.js
+++ b/papaparse.js
@@ -903,7 +903,8 @@
 					}
 				}
 
-				avgFieldCount /= preview.data.length;
+				if (preview.data.length > 0)
+					avgFieldCount /= preview.data.length;
 
 				if ((typeof bestDelta === 'undefined' || delta < bestDelta)
 					&& avgFieldCount > 1.99)