Before this commit, the JS parser would add 0 after the input, then add the ean key. Whereas reportlab.graphics.barcode fills the input with 0's on the left, then add the key http://pydoc.net/Python/reportlab/2.5/reportlab.graphics.barcode.eanbc/ At: Ean13BarcodeWidget.__init__() This commit makes the ean parser coherent with the lib the python uses