diff --git a/CHANGELOG.md b/CHANGELOG.md
index e6501105..e702e5de 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 Version 176:
 
 * Tidy up Quick Reference
+* Fix array end calculation in utf8 assertion
 
 --------------------------------------------------------------------------------
 
diff --git a/include/boost/beast/websocket/detail/utf8_checker.hpp b/include/boost/beast/websocket/detail/utf8_checker.hpp
index 61c241bc..42dbe135 100644
--- a/include/boost/beast/websocket/detail/utf8_checker.hpp
+++ b/include/boost/beast/websocket/detail/utf8_checker.hpp
@@ -194,7 +194,7 @@ write(std::uint8_t const* in, std::size_t size)
         // Add characters to the code point
         while(n--)
             *p_++ = *in++;
-        BOOST_ASSERT(p_ <= cp_ + 5);
+        BOOST_ASSERT(p_ <= cp_ + 4);
 
         // Still incomplete?
         if(need_ > 0)
@@ -313,7 +313,7 @@ tail:
             while(n--)
                 *p_++ = *in++;
             BOOST_ASSERT(in == end);
-            BOOST_ASSERT(p_ <= cp_ + 5);
+            BOOST_ASSERT(p_ <= cp_ + 4);
 
             // Do partial validation on the incomplete
             // code point, this is called "Fail fast"