diff --git a/module3/exo3/weekly_in_situ_co2_mlomodified.csv b/module3/exo3/weekly_in_situ_co2_mlomodified.csv
index 8f708bbd1d9ab4dba08ddd0c3663d5ded0f7eedb..e55779504d0f3c9667c0e116829cad34e637f741 100644
--- a/module3/exo3/weekly_in_situ_co2_mlomodified.csv
+++ b/module3/exo3/weekly_in_situ_co2_mlomodified.csv
@@ -42,7 +42,7 @@
 " SIO manometric mole fraction scale.  These weekly values have been     "
 " adjusted to 12:00 hours at middle day of each weekly period as         "
 " indicated by the date in the first column.                             "
-Date, Concentration
+Date,Concentration
 1958-03-29, 316.19
 1958-04-05, 317.31
 1958-04-12, 317.69