diff --git a/acme.sh b/acme.sh
index 6eee183c..37e925cc 100755
--- a/acme.sh
+++ b/acme.sh
@@ -1829,7 +1829,7 @@ _send_signed_request() {
 
       _debug2 _headers "$_headers"
 
-      _CACHED_NONCE="$(echo "$_headers" | grep "Replay-Nonce:" | _head_n 1 | tr -d "\r\n " | cut -d ':' -f 2)"
+      _CACHED_NONCE="$(echo "$_headers" | grep -i "Replay-Nonce:" | _head_n 1 | tr -d "\r\n " | cut -d ':' -f 2)"
       _debug2 _CACHED_NONCE "$_CACHED_NONCE"
     else
       _debug2 "Use _CACHED_NONCE" "$_CACHED_NONCE"
@@ -3267,7 +3267,7 @@ _regAccount() {
   fi
 
   _debug2 responseHeaders "$responseHeaders"
-  _accUri="$(echo "$responseHeaders" | grep "^Location:" | _head_n 1 | cut -d ' ' -f 2 | tr -d "\r\n")"
+  _accUri="$(echo "$responseHeaders" | grep -i "^Location:" | _head_n 1 | cut -d ' ' -f 2 | tr -d "\r\n")"
   _debug "_accUri" "$_accUri"
   if [ -z "$_accUri" ]; then
     _err "Can not find account id url."
@@ -4947,7 +4947,7 @@ _deactivate() {
       return 1
     fi
 
-    authzUri="$(echo "$responseHeaders" | grep "^Location:" | _head_n 1 | cut -d ' ' -f 2 | tr -d "\r\n")"
+    authzUri="$(echo "$responseHeaders" | grep -i "^Location:" | _head_n 1 | cut -d ' ' -f 2 | tr -d "\r\n")"
     _debug "authzUri" "$authzUri"
     if [ "$code" ] && [ ! "$code" = '201' ]; then
       _err "new-authz error: $response"