diff --git a/assembler.js b/assembler.js
index 01074d3..d30c41c 100644
--- a/assembler.js
+++ b/assembler.js
@@ -63,7 +63,7 @@ const mnemonics2opcodes = {
 function preparseSourceCode(source) {
   let lines = source.split(/\n/); // returns an array of lines
 
-  const isLineBlank = (l) => { return l.length === 0 ? true : false };
+  const isLineBlank = (l) => { return stripWhitespaceFromEnds(l).length === 0 ? true : false };
   const isLineComment = (l) => { return stripWhitespaceFromEnds(l).startsWith(';') };
 
   /**