diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 9b9ababd..e7da5111 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -21,25 +21,36 @@ on:
 env:
   BUILD_TYPE: Release
   CH_SERVER_VERSION: 21.3.17.2
-
 jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        build: [gcc-7, clang-6]
+        build: [clang-6, gcc-7, gcc-8, gcc-9]
         include:
+        - build: clang-6
+          os: ubuntu-latest
+          INSTALL: clang-6.0
+          C_COMPILER: clang-6.0
+          CXX_COMPILER: clang++-6.0
+
         - build: gcc-7
           os: ubuntu-latest
           INSTALL: gcc-7 g++-7
           C_COMPILER: gcc-7
           CXX_COMPILER: g++-7
 
-        - build: clang-6
+        - build: gcc-8
           os: ubuntu-latest
-          INSTALL: clang-6.0
-          C_COMPILER: clang-6.0
-          CXX_COMPILER: clang++-6.0
+          INSTALL: gcc-8 g++-8
+          C_COMPILER: gcc-8
+          CXX_COMPILER: g++-8
+
+        - build: gcc-9
+          os: ubuntu-latest
+          INSTALL: gcc-9 g++-9
+          C_COMPILER: gcc-9
+          CXX_COMPILER: g++-9
 
     steps:
     - uses: actions/checkout@v2
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 707c173e..35b5825f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,6 +22,7 @@ PROJECT (CLICKHOUSE-CLIENT)
             SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread")
         ENDIF ()
         SET (CMAKE_EXE_LINKER_FLAGS, "${CMAKE_EXE_LINKER_FLAGS} -lpthread")
+        # -Wpedantic makes int128 support somewhat harder and less performant (by not allowing builtin __int128)
         SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror")
     ENDIF ()
 
diff --git a/clickhouse/base/sslsocket.cpp b/clickhouse/base/sslsocket.cpp
index 6a78405f..41c9748a 100644
--- a/clickhouse/base/sslsocket.cpp
+++ b/clickhouse/base/sslsocket.cpp
@@ -123,7 +123,7 @@ SSL_CTX * SSLContext::getContext() {
 #define HANDLE_SSL_ERROR(SSL_PTR, statement) [&] { \
     if (const auto ret_code = (statement); ret_code <= 0) { \
         throwSSLError(SSL_PTR, SSL_get_error(SSL_PTR, ret_code), LOCATION, #statement); \
-        return static_cast<decltype(ret_code)>(0); \
+        return static_cast<std::decay_t<decltype(ret_code)>>(0); \
     } \
     else \
         return ret_code; \