In a recent paper, the authors report the analysis of ionospheric TEC data from GPS measurements around the time of the 6 April 2009 L'Aquila earthquake. According to them, an anomalous change in TEC difference from two GPS receivers in central Italy may be explained as related to the earthquake. We have conducted our own independent analysis using the same GPS data. We have shown that in TEC difference there is no evidence of actual seismogenic effects close to the time of L'Aquila earthquake.