diff --git a/src/tools/mpirun/mpirun.c b/src/tools/mpirun/mpirun.c
index 1a60c250b0..c1fcd4d7ae 100644
--- a/src/tools/mpirun/mpirun.c
+++ b/src/tools/mpirun/mpirun.c
@@ -205,7 +205,7 @@ main(int argc, char *argv[])
          * an API rather than setenv.  But we don't have such an API just
          * yet. */
         char *buf = NULL;
-        asprintf(&buf, "OMPI_MCA_hostfile=%s", 
+        asprintf(&buf, "OMPI_MCA_llm_hostfile_hostfile=%s", 
                  ompi_cmd_line_get_param(cmd_line, "hostfile", 0, 0));
         /* yeah, it leaks.  Can't do nothin' about that */
         putenv(buf);