diff --git a/ssh_filter_btrbk.sh b/ssh_filter_btrbk.sh
index b9b4a36..76de95e 100755
--- a/ssh_filter_btrbk.sh
+++ b/ssh_filter_btrbk.sh
@@ -102,12 +102,12 @@ reject_filtered_cmd()
     # when an error occurred.
 
     allow_stream_match="^${stream_in_match}${allow_cmd_match}${stream_out_match}"
-    if printf '%s' "${SSH_ORIGINAL_COMMAND}" | grep -Eq -- "${allow_stream_match}"; then
+    if printf '%s' "${SSH_ORIGINAL_COMMAND}" | grep -E -- "${allow_stream_match}"; then
         return 0
     fi
 
     exact_cmd_match="^(${allow_exact_list})$";
-    if printf '%s' "${SSH_ORIGINAL_COMMAND}" | grep -Eq -- "${exact_cmd_match}"; then
+    if printf '%s' "${SSH_ORIGINAL_COMMAND}" | grep -E -- "${exact_cmd_match}"; then
         return 0
     fi