diff --git a/src/common/execio.h b/src/common/execio.h
--- a/src/common/execio.h
+++ b/src/common/execio.h
@@ -44,17 +44,27 @@ struct execio
 };
 
 /**
-  runs progname with the arguments in argv. argv must be null terminated!!!!!!!!!
-
-  returns nonzero return on error
+ * \brief
+ *   runs progname with the arguments in argv. argv must be null terminated!!!!!!!!!
+ *
+ * \param eio
+ *   Where to store the pointer to the execio handle.
+ * \param progname
+ *   The name of the program to execute at the system's shell.
+ * \param argv
+ *   The NULL-terminated list of arguments to send to the subcommand.
+ * \param nice_incr
+ *   The amount to increase the subprogram's nice value by. See nice(3p).
+ * \return
+ *   nonzero return on error
 */
-int execio_open(struct execio **eio, const char *progname, char *const argv[]);
+int execio_open(struct execio **eio, const char *progname, char *const argv[], int nice_incr);
 
 /**
    doesn't block,
    returns 0 on success, 1 on failure
 */
-int execio_read(struct execio *eio, const void *buf, size_t len, size_t *bytesread);
+int execio_read(struct execio *eio, void *buf, size_t len, size_t *bytesread);
 int execio_write(struct execio *eio, const void *buf, size_t len, size_t *byteswritten);
 
 /**