diff --git a/src/Subscription.h b/src/Subscription.h
index 02851bb..037bf6e 100644
--- a/src/Subscription.h
+++ b/src/Subscription.h
@@ -4,11 +4,11 @@
 
 
 struct SubId {
-    char buf[40];
+    char buf[64];
 
     SubId(std::string_view val) {
-        static_assert(MAX_SUBID_SIZE == 39, "MAX_SUBID_SIZE mismatch");
-        if (val.size() > 39) throw herr("subscription id too long");
+        static_assert(MAX_SUBID_SIZE == 63, "MAX_SUBID_SIZE mismatch");
+        if (val.size() > 63) throw herr("subscription id too long");
         if (val.size() == 0) throw herr("subscription id too short");
 
         auto badChar = [](char c){
diff --git a/src/constants.h b/src/constants.h
index 9d27dc3..fb10191 100644
--- a/src/constants.h
+++ b/src/constants.h
@@ -1,3 +1,3 @@
 #pragma once
 
-const size_t MAX_SUBID_SIZE = 39;
+const size_t MAX_SUBID_SIZE = 63;