diff --git a/dehydrated b/dehydrated
index 41a3614..9d9bca5 100755
--- a/dehydrated
+++ b/dehydrated
@@ -579,9 +579,9 @@ signed_request() {
 
   # Retrieve nonce from acme-server
   if [[ ${API} -eq 1 ]]; then
-    nonce="$(http_request head "${CA}" | grep -i Replay-Nonce: | awk -F ': ' '{print $2}' | tr -d '\n\r')"
+    nonce="$(http_request head "${CA}" | grep -i ^Replay-Nonce: | awk -F ': ' '{print $2}' | tr -d '\n\r')"
   else
-    nonce="$(http_request head "${CA_NEW_NONCE}" | grep -i Replay-Nonce: | awk -F ': ' '{print $2}' | tr -d '\n\r')"
+    nonce="$(http_request head "${CA_NEW_NONCE}" | grep -i ^Replay-Nonce: | awk -F ': ' '{print $2}' | tr -d '\n\r')"
   fi
 
   # Build header with just our public key and algorithm information