diff --git a/services/filestore/app/coffee/ImageOptimiser.coffee b/services/filestore/app/coffee/ImageOptimiser.coffee
index fb2001a1d0..4888e00224 100644
--- a/services/filestore/app/coffee/ImageOptimiser.coffee
+++ b/services/filestore/app/coffee/ImageOptimiser.coffee
@@ -11,13 +11,11 @@ module.exports =
 			timeout: 30 * 1000
 			killSignal: "SIGKILL"
 		exec args, opts,(err, stdout, stderr)->
-			if err?
-				if err.signal == 'SIGKILL'
-					logger.warn {err: err, stderr: stderr, localPath: localPath}, "optimiser timeout reached"
-					err = null
-				else
-					logger.err err:err, stderr:stderr, localPath:localPath, "something went wrong converting compressPng"
+			if err? and err.signal == 'SIGKILL'
+				logger.warn {err: err, stderr: stderr, localPath: localPath}, "optimiser timeout reached"
+				err = null
+			else if err?
+				logger.err err:err, stderr:stderr, localPath:localPath, "something went wrong converting compressPng"
 			else
 				logger.log  localPath:localPath, "finished compressPng file"
 			callback(err)
-