diff --git a/examples/http_async_server.hpp b/examples/http_async_server.hpp
index 501aa8a5..791e6bf7 100644
--- a/examples/http_async_server.hpp
+++ b/examples/http_async_server.hpp
@@ -15,6 +15,7 @@
 #include <beast/core/placeholders.hpp>
 #include <beast/core/streambuf.hpp>
 #include <boost/asio.hpp>
+#include <cstddef>
 #include <cstdio>
 #include <iostream>
 #include <memory>
@@ -44,7 +45,7 @@ class http_async_server
 
 public:
     http_async_server(endpoint_type const& ep,
-            int threads, std::string const& root)
+            std::size_t threads, std::string const& root)
         : acceptor_(ios_)
         , sock_(ios_)
         , root_(root)
@@ -57,7 +58,7 @@ public:
             std::bind(&http_async_server::on_accept, this,
                 beast::asio::placeholders::error));
         thread_.reserve(threads);
-        for(int i = 0; i < threads; ++i)
+        for(std::size_t i = 0; i < threads; ++i)
             thread_.emplace_back(
                 [&] { ios_.run(); });
     }
diff --git a/include/beast/core/detail/base64.hpp b/include/beast/core/detail/base64.hpp
index 0256aa7d..5c65a1e0 100644
--- a/include/beast/core/detail/base64.hpp
+++ b/include/beast/core/detail/base64.hpp
@@ -124,7 +124,7 @@ template <class = void>
 std::string
 base64_decode(std::string const& data)
 {
-    int in_len = data.size();
+    auto in_len = data.size();
     unsigned char c3[3], c4[4];
     int i = 0;
     int j = 0;
diff --git a/include/beast/websocket/detail/mask.hpp b/include/beast/websocket/detail/mask.hpp
index 78f6f1f8..fb67b511 100644
--- a/include/beast/websocket/detail/mask.hpp
+++ b/include/beast/websocket/detail/mask.hpp
@@ -113,7 +113,7 @@ mask_inplace_general(
 {
     using boost::asio::buffer_cast;
     using boost::asio::buffer_size;
-    auto n = buffer_size(b);
+    auto const n = buffer_size(b);
     auto p = buffer_cast<std::uint8_t*>(b);
     for(auto i = n / sizeof(key); i; --i)
     {
@@ -122,13 +122,14 @@ mask_inplace_general(
         *p ^= (key >>16); ++p;
         *p ^= (key >>24); ++p;
     }
-    n %= sizeof(key);
-    switch(n)
+    auto const m =
+        static_cast<std::uint8_t>(n % sizeof(key));
+    switch(m)
     {
     case 3: p[2] ^= (key >>16);
     case 2: p[1] ^= (key >> 8);
     case 1: p[0] ^=  key;
-        key = ror(key, n*8);
+        key = ror(key, m*8);
     default:
         break;
     }
@@ -144,7 +145,7 @@ mask_inplace_general(
 {
     using boost::asio::buffer_cast;
     using boost::asio::buffer_size;
-    auto n = buffer_size(b);
+    auto const n = buffer_size(b);
     auto p = buffer_cast<std::uint8_t*>(b);
     for(auto i = n / sizeof(key); i; --i)
     {
@@ -157,8 +158,9 @@ mask_inplace_general(
         *p ^= (key >>48); ++p;
         *p ^= (key >>56); ++p;
     }
-    n %= sizeof(key);
-    switch(n)
+    auto const m =
+        static_cast<std::uint8_t>(n % sizeof(key));
+    switch(m)
     {
     case 7: p[6] ^= (key >>16);
     case 6: p[5] ^= (key >> 8);
@@ -167,7 +169,7 @@ mask_inplace_general(
     case 3: p[2] ^= (key >>16);
     case 2: p[1] ^= (key >> 8);
     case 1: p[0] ^=  key;
-        key = ror(key, n*8);
+        key = ror(key, m*8);
     default:
         break;
     }