diff --git a/cpp/opengl/render_context.hpp b/cpp/opengl/render_context.hpp
index 6c95218..8e8ff74 100644
--- a/cpp/opengl/render_context.hpp
+++ b/cpp/opengl/render_context.hpp
@@ -22,12 +22,12 @@
 extern PFNGLDRAWELEMENTSINSTANCEDBASEINSTANCEPROC rk_DrawElementsInstancedBaseInstance;
 extern PFNGLMULTIDRAWELEMENTSINDIRECTPROC rk_MultiDrawElementsIndirect;
 
-RK_EXPORT rk_window_t rk_create_context(
+extern rk_window_t rk_create_context(
     char const * name,
-    rk_uint width,
-    rk_uint height);
+    unsigned width,
+    unsigned height);
 
-RK_EXPORT void rk_swap_buffers();
-RK_EXPORT void rk_destroy_context();
+extern void rk_swap_buffers();
+extern void rk_destroy_context();
 
 #endif // _RK_ENGINE_RENDER_CONTEXT_H
diff --git a/cpp/opengl/render_context_glx.cpp b/cpp/opengl/render_context_glx.cpp
index c8f8c73..dbf8f40 100644
--- a/cpp/opengl/render_context_glx.cpp
+++ b/cpp/opengl/render_context_glx.cpp
@@ -91,8 +91,8 @@ static int rk_error_handler(
 
 rk_window_t rk_create_context(
     char const * name,
-    rk_uint width,
-    rk_uint height) {
+    unsigned width,
+    unsigned height) {
     rk_display = XOpenDisplay(nullptr);
     if (!rk_display) {
         rk_printf("Failed to open X display.");
@@ -162,7 +162,7 @@ rk_window_t rk_create_context(
     char const * const glx_exts = glXQueryExtensionsString(rk_display, DefaultScreen(rk_display));
     glXCreateContextAttribsARBProc const glXCreateContextAttribsARB =
         reinterpret_cast<glXCreateContextAttribsARBProc>(
-            glXGetProcAddressARB(reinterpret_cast<const GLubyte *>("glXCreateContextAttribsARB")));
+            glXGetProcAddressARB(reinterpret_cast<GLubyte const *>("glXCreateContextAttribsARB")));
 
     rk_error_occured = false;
     int (*oldHandler)(Display *, XErrorEvent *) = XSetErrorHandler(&rk_error_handler);
@@ -190,13 +190,13 @@ rk_window_t rk_create_context(
     if (rk_extension_supported(gl_exts, "GL_EXT_base_instance")) {
         rk_DrawElementsInstancedBaseInstance =
             reinterpret_cast<PFNGLDRAWELEMENTSINSTANCEDBASEINSTANCEPROC>(
-                glXGetProcAddressARB(reinterpret_cast<const GLubyte *>("DrawElementsInstancedBaseInstance")));
+                glXGetProcAddressARB(reinterpret_cast<GLubyte const *>("DrawElementsInstancedBaseInstance")));
         if (rk_DrawElementsInstancedBaseInstance) {
             rk_printf("Using extension GL_EXT_base_instance::DrawElementsInstancedBaseInstance.");
             if (rk_extension_supported(gl_exts, "GL_EXT_multi_draw_indirect")) {
                 rk_MultiDrawElementsIndirect =
                     reinterpret_cast<PFNGLMULTIDRAWELEMENTSINDIRECTPROC>(
-                        glXGetProcAddressARB(reinterpret_cast<const GLubyte *>("MultiDrawElementsIndirectEXT")));
+                        glXGetProcAddressARB(reinterpret_cast<GLubyte const *>("MultiDrawElementsIndirectEXT")));
                 if (rk_MultiDrawElementsIndirect) {
                     rk_printf("Using extension GL_EXT_multi_draw_indirect::MultiDrawElementsIndirectEXT.");
                 }
diff --git a/cpp/opengl/render_opengles.cpp b/cpp/opengl/render_opengles.cpp
index 91d988b..bb80145 100644
--- a/cpp/opengl/render_opengles.cpp
+++ b/cpp/opengl/render_opengles.cpp
@@ -66,7 +66,7 @@ rk_window_t rk_initialize(
 }
 
 static void rk_print_shader_infolog(GLuint shader) {
-    int length;
+    GLsizei length;
     char infolog[1024];
     glGetShaderInfoLog(shader, sizeof(infolog), &length, infolog);
     if (length > 0) {
@@ -75,7 +75,7 @@ static void rk_print_shader_infolog(GLuint shader) {
 }
 
 static void rk_print_program_infolog(GLuint program) {
-    int length;
+    GLsizei length;
     char infolog[1024];
     glGetProgramInfoLog(program, sizeof(infolog), &length, infolog);
     if (length > 0) {
@@ -258,7 +258,7 @@ rk_vertices_t rk_create_vertices(
     if (!format || !nvertices || !_vertices || !nindices || !indices) {
         return nullptr;
     }
-    rk_uint vertex_size = 0;
+    unsigned vertex_size = 0;
     for (rk_vertex_format const * f = format; *f; ++f) {
         switch (*f & RK_VERTEX_FORMAT_MASK) {
             case RK_VERTEX_FORMAT_VEC3_FLOAT:
@@ -289,7 +289,7 @@ rk_vertices_t rk_create_vertices(
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     vertices->vertex_size = vertex_size;
     vertices->layout = 0;
-    rk_uint offset = 0;
+    unsigned offset = 0;
     for (rk_vertex_format const * f = format; *f; ++f, ++vertices->layout) {
         glEnableVertexAttribArray(vertices->layout);
         GLboolean const normalize = (*f & RK_VERTEX_FORMAT_NORMALIZE) != 0;
@@ -359,9 +359,9 @@ rk_batch_t rk_create_batch(
         rk_printf("rk_create_batch(): invalid parameters.");
         return nullptr;
     }
-    rk_uint nparams = 0;
-    rk_uint params_size = 0;
-    rk_uint packed_size = 0;
+    unsigned nparams = 0;
+    unsigned params_size = 0;
+    unsigned packed_size = 0;
     for (rk_param_format const * f = params_format; *f; ++f, ++nparams) {
         switch (*f & RK_PARAM_FORMAT_MASK) {
             case RK_PARAM_FORMAT_VEC3_FLOAT:
@@ -393,9 +393,9 @@ rk_batch_t rk_create_batch(
         batch->packers = new rk_packer[nparams];
         batch->params = new rk_ubyte[max_size * packed_size];
         glGenBuffers(1, &batch->params_buffer);
-        rk_uint layout = vertices->layout;
+        unsigned layout = vertices->layout;
         rk_packer * packer = batch->packers;
-        rk_uint offset = 0;
+        unsigned offset = 0;
         glBindVertexArray(vertices->array);
         for (rk_param_format const * f = params_format; *f; ++f, ++layout, ++packer) {
             GLboolean const normalize = (*f & RK_PARAM_FORMAT_NORMALIZE) != 0;
@@ -531,22 +531,22 @@ void rk_select_vertices(
     }
 }
 
-static rk_uint rk_batch_filter(
+static unsigned rk_batch_filter(
     rk_batch & batch,
-    rk_uint const size,
+    unsigned const size,
     rk_instance_flags const * flags) {
     rk_ushort * indices = batch.indices;
-    for (rk_ushort index = 0; index < size; ++index, ++flags) {
+    for (unsigned index = 0; index < size; ++index, ++flags) {
         if ((*flags & RK_INSTANCE_FLAGS_SPAWNED_VISIBLE) == RK_INSTANCE_FLAGS_SPAWNED_VISIBLE) {
-            *indices++ = index;
+            *indices++ = static_cast<rk_ushort>(index);
         }
     }
     return indices - batch.indices;
 }
 
-static rk_uint rk_batch_build_commands(
+static unsigned rk_batch_build_commands(
     rk_batch & batch,
-    rk_uint const ninstances,
+    unsigned const ninstances,
     rk_mesh const * const meshes) {
     rk_command * commands = batch.commands;
     rk_ushort * base = batch.indices;
@@ -556,10 +556,10 @@ static rk_uint rk_batch_build_commands(
         for ( ; first < last && meshes[*first].packed == mesh.packed; ++first) {
         }
         for (rk_ushort * second = first; second < last; ++second) {
-            rk_ushort const index = *second;
+            unsigned const index = *second;
             if (meshes[index].packed == mesh.packed) {
                 *second = *first;
-                *first++ = index;
+                *first++ = static_cast<rk_ushort>(index);
             }
         }
         commands->nvertices = static_cast<GLuint>(mesh.ntriangles) * 3;
@@ -573,7 +573,7 @@ static rk_uint rk_batch_build_commands(
 
 static void rk_batch_pack(
     rk_batch & batch,
-    rk_uint const ninstances,
+    unsigned const ninstances,
     rk_ubyte const * const params) {
     rk_pack_dst dst(batch.params);
     rk_ushort const * const last_index = batch.indices + ninstances;
@@ -598,11 +598,11 @@ void rk_draw_batch(
     if (!size || size > batch.size || !flags || !meshes || !rk_current_shader || !rk_current_vertices) {
         return;
     }
-    rk_uint const ninstances = rk_batch_filter(batch, size, flags);
+    unsigned const ninstances = rk_batch_filter(batch, size, flags);
     if (!ninstances) {
         return;
     }
-    rk_uint const ncommands = rk_batch_build_commands(batch, ninstances, meshes);
+    unsigned const ncommands = rk_batch_build_commands(batch, ninstances, meshes);
     if (rk_MultiDrawElementsIndirect) {
         glBindBuffer(GL_DRAW_INDIRECT_BUFFER, batch.commands_buffer);
         glBufferData(GL_DRAW_INDIRECT_BUFFER, ncommands * sizeof(rk_command), batch.commands, GL_STREAM_DRAW);
@@ -627,7 +627,7 @@ void rk_draw_batch(
             }
         }
     } else {
-        rk_uint params_offset = 0;
+        unsigned params_offset = 0;
         rk_command const * const last_command = batch.commands + ncommands;
         for (rk_command const * command = batch.commands; command < last_command; ++command) {
             if (batch.nparams) {
diff --git a/cpp/opengl/render_opengles.hpp b/cpp/opengl/render_opengles.hpp
index 3829415..d73d160 100644
--- a/cpp/opengl/render_opengles.hpp
+++ b/cpp/opengl/render_opengles.hpp
@@ -22,7 +22,7 @@
 #include <GLES3/gl3ext.h>
 #include <GLES3/gl3platform.h>
 
-enum : rk_uint {
+enum : GLuint {
     RK_VERTICES_BINDING = 0,
     RK_PARAMS_BINDING = 1
 };
@@ -34,19 +34,19 @@ struct rk_shader {
 };
 
 struct rk_texture {
-    rk_uint nlevels;
+    unsigned nlevels;
     GLuint texture;
 };
 
 struct rk_triangles {
-    rk_uint size;
+    unsigned size;
     GLuint array;
     GLuint vertices;
 };
 
 struct rk_vertices {
-    rk_uint vertex_size;
-    rk_uint layout;
+    unsigned vertex_size;
+    unsigned layout;
     GLuint array;
     GLuint vertices;
     GLuint indices;
@@ -81,8 +81,8 @@ typedef void (*rk_packer_fn)(rk_pack_dst, rk_pack_src);
 
 struct rk_packer {
     rk_packer_fn pack;
-    rk_uint dst_incr;
-    rk_uint src_incr;
+    unsigned dst_incr;
+    unsigned src_incr;
 };
 
 struct rk_command {
@@ -94,10 +94,10 @@ struct rk_command {
 };
 
 struct rk_batch {
-    rk_uint size;
-    rk_uint nparams;
-    rk_uint params_size;
-    rk_uint packed_size;
+    unsigned size;
+    unsigned nparams;
+    unsigned params_size;
+    unsigned packed_size;
     rk_ushort * indices;
     rk_command * commands;
     rk_packer * packers;