You probably want to set the shell's pipefail option:

  pipefail

          If set, the return value of a  pipeline  is  the

          value  of  the  last (rightmost) command to exit

          with a non-zero status, or zero if all  commands

          in  the pipeline exit successfully.  This option

          is disabled by default.

So, set -eo pipefail in place of just set -e. See also Retrieving status code when using pipelines.