diff --git a/docker/Dockerfile.centos8-cpp-env b/docker/Dockerfile.centos8-cpp-env
new file mode 100644
index 000000000..0bcda9d56
--- /dev/null
+++ b/docker/Dockerfile.centos8-cpp-env
@@ -0,0 +1,27 @@
+# CLion remote docker environment (How to build docker container, run and stop it)
+#
+# Build:
+#   docker build -t build/centos-8/cpp-env:1.0 -f Dockerfile.centos8-cpp-env .
+
+FROM centos:8
+
+RUN yum -y update && yum -y install dnf-plugins-core && yum config-manager --set-enabled powertools && yum -y install \
+  openssh-server \
+  make \
+  autoconf \
+  automake \
+  dos2unix \
+  gcc \
+  gcc-c++ \
+  gdb \
+  clang \
+  cmake \
+  rsync \
+  tar \
+  python39 \
+  doxygen \
+  graphviz \
+  swig \
+  ninja-build \
+  wget \
+ && yum clean all
diff --git a/docker/Dockerfile.ubuntu20-cpp-env b/docker/Dockerfile.ubuntu20-cpp-env
new file mode 100644
index 000000000..79a33f774
--- /dev/null
+++ b/docker/Dockerfile.ubuntu20-cpp-env
@@ -0,0 +1,28 @@
+# Build and run:
+#   docker build -t build/ubuntu-20.04/cpp-env:1.0 -f Dockerfile.ubuntu20-cpp-env .
+
+FROM ubuntu:20.04
+
+RUN DEBIAN_FRONTEND="noninteractive" apt-get update && apt-get -y install tzdata
+RUN apt-get update && apt-get -y install \
+  build-essential \
+  gcc \
+  g++ \
+  gdb \
+  clang \
+  make \
+  ninja-build \
+  cmake \
+  autoconf \
+  automake \
+  locales-all \
+  dos2unix \
+  rsync \
+  tar \
+  python \
+  python-dev \
+  doxygen \
+  graphviz \
+  swig \
+  wget \
+  && apt-get clean
diff --git a/src/omega_edit/src/encodings.c b/src/omega_edit/src/encodings.c
index 0eecfd23f..1093192e3 100644
--- a/src/omega_edit/src/encodings.c
+++ b/src/omega_edit/src/encodings.c
@@ -19,9 +19,9 @@ size_t omega_bin2hex(const omega_byte_t *src, char *dst, size_t src_length) {
     assert(src);
     assert(dst);
     static const char HEX_CONVERSION_TABLE[] = "0123456789abcdef";
-    size_t j = 0;
+    size_t i, j = 0;
 
-    for (size_t i = 0; i < src_length; ++i) {
+    for (i = 0; i < src_length; ++i) {
         dst[j++] = HEX_CONVERSION_TABLE[src[i] >> 4];
         dst[j++] = HEX_CONVERSION_TABLE[src[i] & 15];
     }
diff --git a/src/omega_edit/src/impl_/session_def.hpp b/src/omega_edit/src/impl_/session_def.hpp
index 69a8f583e..0e769a283 100644
--- a/src/omega_edit/src/impl_/session_def.hpp
+++ b/src/omega_edit/src/impl_/session_def.hpp
@@ -18,6 +18,7 @@
 #include "../../include/edit.h"
 #include "../../include/fwd_defs.h"
 #include "internal_fwd_defs.hpp"
+#include "model_def.hpp"
 #include <cstdio>
 #include <string>
 #include <vector>
diff --git a/src/omega_edit/src/utility.c b/src/omega_edit/src/utility.c
index df63135c6..f3c6ab04d 100644
--- a/src/omega_edit/src/utility.c
+++ b/src/omega_edit/src/utility.c
@@ -40,7 +40,8 @@ int omega_util_file_exists(const char *file_name) {
 
 void omega_util_byte_transformer(omega_byte_t *buffer, int64_t len, omega_util_byte_transform_t transform) {
     assert(buffer);
-    for (int64_t i = 0; i < len; ++i) { buffer[i] = transform(buffer[i]); }
+    int64_t i;
+    for (i = 0; i < len; ++i) { buffer[i] = transform(buffer[i]); }
 }
 
 int omega_util_left_shift_buffer(omega_byte_t *buffer, int64_t len, omega_byte_t shift_left) {
@@ -49,7 +50,8 @@ int omega_util_left_shift_buffer(omega_byte_t *buffer, int64_t len, omega_byte_t
         omega_byte_t shift_right = 8 - shift_left;
         omega_byte_t mask = ((1 << shift_left) - 1) << shift_right;
         omega_byte_t bits1 = 0;
-        for (int64_t i = len - 1; i >= 0; --i) {
+        int64_t i;
+        for (i = len - 1; i >= 0; --i) {
             const unsigned char bits2 = buffer[i] & mask;
             buffer[i] <<= shift_left;
             buffer[i] |= bits1 >> shift_right;
@@ -66,7 +68,8 @@ int omega_util_right_shift_buffer(omega_byte_t *buffer, int64_t len, omega_byte_
         omega_byte_t shift_left = 8 - shift_right;
         omega_byte_t mask = (1 << shift_right) - 1;
         omega_byte_t bits1 = 0;
-        for (int64_t i = len - 1; i >= 0; --i) {
+        int64_t i;
+        for (i = len - 1; i >= 0; --i) {
             const unsigned char bits2 = buffer[i] & mask;
             buffer[i] >>= shift_right;
             buffer[i] |= bits1 << shift_left;