diff --git a/src/libtrx/gfx/gl/buffer.c b/src/libtrx/gfx/gl/buffer.c
index aed161a43..f2aa5538a 100644
--- a/src/libtrx/gfx/gl/buffer.c
+++ b/src/libtrx/gfx/gl/buffer.c
@@ -6,22 +6,27 @@
 
 void GFX_GL_Buffer_Init(GFX_GL_BUFFER *buf, GLenum target)
 {
-    assert(buf);
+    assert(buf != NULL);
     buf->target = target;
     glGenBuffers(1, &buf->id);
     GFX_GL_CheckError();
+    buf->initialized = true;
 }
 
 void GFX_GL_Buffer_Close(GFX_GL_BUFFER *buf)
 {
-    assert(buf);
-    glDeleteBuffers(1, &buf->id);
-    GFX_GL_CheckError();
+    assert(buf != NULL);
+    if (buf->initialized) {
+        glDeleteBuffers(1, &buf->id);
+        GFX_GL_CheckError();
+    }
+    buf->initialized = false;
 }
 
 void GFX_GL_Buffer_Bind(GFX_GL_BUFFER *buf)
 {
-    assert(buf);
+    assert(buf != NULL);
+    assert(buf->initialized);
     glBindBuffer(buf->target, buf->id);
     GFX_GL_CheckError();
 }
@@ -29,7 +34,8 @@ void GFX_GL_Buffer_Bind(GFX_GL_BUFFER *buf)
 void GFX_GL_Buffer_Data(
     GFX_GL_BUFFER *buf, GLsizei size, const void *data, GLenum usage)
 {
-    assert(buf);
+    assert(buf != NULL);
+    assert(buf->initialized);
     glBufferData(buf->target, size, data, usage);
     GFX_GL_CheckError();
 }
@@ -37,14 +43,16 @@ void GFX_GL_Buffer_Data(
 void GFX_GL_Buffer_SubData(
     GFX_GL_BUFFER *buf, GLsizei offset, GLsizei size, const void *data)
 {
-    assert(buf);
+    assert(buf != NULL);
+    assert(buf->initialized);
     glBufferSubData(buf->target, offset, size, data);
     GFX_GL_CheckError();
 }
 
 void *GFX_GL_Buffer_Map(GFX_GL_BUFFER *buf, GLenum access)
 {
-    assert(buf);
+    assert(buf != NULL);
+    assert(buf->initialized);
     void *ret = glMapBuffer(buf->target, access);
     GFX_GL_CheckError();
     return ret;
@@ -52,14 +60,16 @@ void *GFX_GL_Buffer_Map(GFX_GL_BUFFER *buf, GLenum access)
 
 void GFX_GL_Buffer_Unmap(GFX_GL_BUFFER *buf)
 {
-    assert(buf);
+    assert(buf != NULL);
+    assert(buf->initialized);
     glUnmapBuffer(buf->target);
     GFX_GL_CheckError();
 }
 
 GLint GFX_GL_Buffer_Parameter(GFX_GL_BUFFER *buf, GLenum pname)
 {
-    assert(buf);
+    assert(buf != NULL);
+    assert(buf->initialized);
     GLint params = 0;
     glGetBufferParameteriv(buf->target, pname, &params);
     GFX_GL_CheckError();
diff --git a/src/libtrx/gfx/gl/program.c b/src/libtrx/gfx/gl/program.c
index a3e65ab92..c45c182bf 100644
--- a/src/libtrx/gfx/gl/program.c
+++ b/src/libtrx/gfx/gl/program.c
@@ -24,6 +24,7 @@ bool GFX_GL_Program_Init(GFX_GL_PROGRAM *program)
 
 void GFX_GL_Program_Close(GFX_GL_PROGRAM *program)
 {
+    assert(program != NULL);
     if (program->id) {
         glDeleteProgram(program->id);
         GFX_GL_CheckError();
@@ -33,6 +34,7 @@ void GFX_GL_Program_Close(GFX_GL_PROGRAM *program)
 
 void GFX_GL_Program_Bind(GFX_GL_PROGRAM *program)
 {
+    assert(program != NULL);
     glUseProgram(program->id);
     GFX_GL_CheckError();
 }
@@ -40,6 +42,8 @@ void GFX_GL_Program_Bind(GFX_GL_PROGRAM *program)
 char *GFX_GL_Program_PreprocessShader(
     const char *content, GLenum type, GFX_GL_BACKEND backend)
 {
+    assert(content != NULL);
+
     const char *version_ogl21 =
         "#version 120\n"
         "#extension GL_ARB_explicit_attrib_location: enable\n"
@@ -85,6 +89,9 @@ char *GFX_GL_Program_PreprocessShader(
 void GFX_GL_Program_AttachShader(
     GFX_GL_PROGRAM *program, GLenum type, const char *path)
 {
+    assert(program != NULL);
+    assert(path != NULL);
+
     GLuint shader_id = glCreateShader(type);
     GFX_GL_CheckError();
     if (!shader_id) {
@@ -137,6 +144,7 @@ void GFX_GL_Program_AttachShader(
 
 void GFX_GL_Program_Link(GFX_GL_PROGRAM *program)
 {
+    assert(program != NULL);
     glLinkProgram(program->id);
     GFX_GL_CheckError();
 
@@ -160,12 +168,14 @@ void GFX_GL_Program_Link(GFX_GL_PROGRAM *program)
 
 void GFX_GL_Program_FragmentData(GFX_GL_PROGRAM *program, const char *name)
 {
+    assert(program != NULL);
     glBindFragDataLocation(program->id, 0, name);
     GFX_GL_CheckError();
 }
 
 GLint GFX_GL_Program_UniformLocation(GFX_GL_PROGRAM *program, const char *name)
 {
+    assert(program != NULL);
     GLint location = glGetUniformLocation(program->id, name);
     GFX_GL_CheckError();
     if (location == -1) {
@@ -177,6 +187,7 @@ GLint GFX_GL_Program_UniformLocation(GFX_GL_PROGRAM *program, const char *name)
 void GFX_GL_Program_Uniform3f(
     GFX_GL_PROGRAM *program, GLint loc, GLfloat v0, GLfloat v1, GLfloat v2)
 {
+    assert(program != NULL);
     glUniform3f(loc, v0, v1, v2);
     GFX_GL_CheckError();
 }
@@ -185,12 +196,14 @@ void GFX_GL_Program_Uniform4f(
     GFX_GL_PROGRAM *program, GLint loc, GLfloat v0, GLfloat v1, GLfloat v2,
     GLfloat v3)
 {
+    assert(program != NULL);
     glUniform4f(loc, v0, v1, v2, v3);
     GFX_GL_CheckError();
 }
 
 void GFX_GL_Program_Uniform1i(GFX_GL_PROGRAM *program, GLint loc, GLint v0)
 {
+    assert(program != NULL);
     glUniform1i(loc, v0);
     GFX_GL_CheckError();
 }
@@ -199,6 +212,7 @@ void GFX_GL_Program_UniformMatrix4fv(
     GFX_GL_PROGRAM *program, GLint loc, GLsizei count, GLboolean transpose,
     const GLfloat *value)
 {
+    assert(program != NULL);
     glUniformMatrix4fv(loc, count, transpose, value);
     GFX_GL_CheckError();
 }
diff --git a/src/libtrx/gfx/gl/sampler.c b/src/libtrx/gfx/gl/sampler.c
index cb76df850..1735693d2 100644
--- a/src/libtrx/gfx/gl/sampler.c
+++ b/src/libtrx/gfx/gl/sampler.c
@@ -2,20 +2,30 @@
 
 #include "gfx/gl/utils.h"
 
+#include <assert.h>
+
 void GFX_GL_Sampler_Init(GFX_GL_SAMPLER *sampler)
 {
+    assert(sampler != NULL);
     glGenSamplers(1, &sampler->id);
     GFX_GL_CheckError();
+    sampler->initialized = true;
 }
 
 void GFX_GL_Sampler_Close(GFX_GL_SAMPLER *sampler)
 {
-    glDeleteSamplers(1, &sampler->id);
-    GFX_GL_CheckError();
+    assert(sampler != NULL);
+    if (sampler->initialized) {
+        glDeleteSamplers(1, &sampler->id);
+        GFX_GL_CheckError();
+    }
+    sampler->initialized = false;
 }
 
 void GFX_GL_Sampler_Bind(GFX_GL_SAMPLER *sampler, GLuint unit)
 {
+    assert(sampler != NULL);
+    assert(sampler->initialized);
     glBindSampler(unit, sampler->id);
     GFX_GL_CheckError();
 }
@@ -23,6 +33,8 @@ void GFX_GL_Sampler_Bind(GFX_GL_SAMPLER *sampler, GLuint unit)
 void GFX_GL_Sampler_Parameteri(
     GFX_GL_SAMPLER *sampler, GLenum pname, GLint param)
 {
+    assert(sampler != NULL);
+    assert(sampler->initialized);
     glSamplerParameteri(sampler->id, pname, param);
     GFX_GL_CheckError();
 }
@@ -30,6 +42,8 @@ void GFX_GL_Sampler_Parameteri(
 void GFX_GL_Sampler_Parameterf(
     GFX_GL_SAMPLER *sampler, GLenum pname, GLfloat param)
 {
+    assert(sampler != NULL);
+    assert(sampler->initialized);
     glSamplerParameterf(sampler->id, pname, param);
     GFX_GL_CheckError();
 }
diff --git a/src/libtrx/gfx/gl/texture.c b/src/libtrx/gfx/gl/texture.c
index f5f067dcd..d0659389e 100644
--- a/src/libtrx/gfx/gl/texture.c
+++ b/src/libtrx/gfx/gl/texture.c
@@ -27,18 +27,23 @@ void GFX_GL_Texture_Init(GFX_GL_TEXTURE *texture, GLenum target)
     texture->target = target;
     glGenTextures(1, &texture->id);
     GFX_GL_CheckError();
+    texture->initialized = true;
 }
 
 void GFX_GL_Texture_Close(GFX_GL_TEXTURE *texture)
 {
     assert(texture != NULL);
-    glDeleteTextures(1, &texture->id);
-    GFX_GL_CheckError();
+    if (texture->initialized) {
+        glDeleteTextures(1, &texture->id);
+        GFX_GL_CheckError();
+    }
+    texture->initialized = false;
 }
 
 void GFX_GL_Texture_Bind(GFX_GL_TEXTURE *texture)
 {
     assert(texture != NULL);
+    assert(texture->initialized);
     glBindTexture(texture->target, texture->id);
     GFX_GL_CheckError();
 }
@@ -48,6 +53,7 @@ void GFX_GL_Texture_Load(
     GLint internal_format, GLint format)
 {
     assert(texture != NULL);
+    assert(texture->initialized);
 
     GFX_GL_Texture_Bind(texture);
 
@@ -65,6 +71,7 @@ void GFX_GL_Texture_Load(
 void GFX_GL_Texture_LoadFromBackBuffer(GFX_GL_TEXTURE *const texture)
 {
     assert(texture != NULL);
+    assert(texture->initialized);
 
     GFX_GL_Texture_Bind(texture);
 
diff --git a/src/libtrx/gfx/gl/vertex_array.c b/src/libtrx/gfx/gl/vertex_array.c
index 6f8903968..461ca531d 100644
--- a/src/libtrx/gfx/gl/vertex_array.c
+++ b/src/libtrx/gfx/gl/vertex_array.c
@@ -7,21 +7,26 @@
 
 void GFX_GL_VertexArray_Init(GFX_GL_VERTEX_ARRAY *array)
 {
-    assert(array);
+    assert(array != NULL);
     glGenVertexArrays(1, &array->id);
     GFX_GL_CheckError();
+    array->initialized = true;
 }
 
 void GFX_GL_VertexArray_Close(GFX_GL_VERTEX_ARRAY *array)
 {
-    assert(array);
-    glDeleteVertexArrays(1, &array->id);
-    GFX_GL_CheckError();
+    assert(array != NULL);
+    if (array->initialized) {
+        glDeleteVertexArrays(1, &array->id);
+        GFX_GL_CheckError();
+    }
+    array->initialized = false;
 }
 
 void GFX_GL_VertexArray_Bind(GFX_GL_VERTEX_ARRAY *array)
 {
-    assert(array);
+    assert(array != NULL);
+    assert(array->initialized);
     glBindVertexArray(array->id);
     GFX_GL_CheckError();
 }
@@ -30,7 +35,8 @@ void GFX_GL_VertexArray_Attribute(
     GFX_GL_VERTEX_ARRAY *array, GLuint index, GLint size, GLenum type,
     GLboolean normalized, GLsizei stride, GLsizei offset)
 {
-    assert(array);
+    assert(array != NULL);
+    assert(array->initialized);
     glEnableVertexAttribArray(index);
     GFX_GL_CheckError();
 
diff --git a/src/libtrx/include/libtrx/gfx/gl/buffer.h b/src/libtrx/include/libtrx/gfx/gl/buffer.h
index 99f8f68c2..d3711cd74 100644
--- a/src/libtrx/include/libtrx/gfx/gl/buffer.h
+++ b/src/libtrx/include/libtrx/gfx/gl/buffer.h
@@ -2,7 +2,10 @@
 
 #include "gl_core_3_3.h"
 
+#include <stdbool.h>
+
 typedef struct {
+    bool initialized;
     GLuint id;
     GLenum target;
 } GFX_GL_BUFFER;
diff --git a/src/libtrx/include/libtrx/gfx/gl/program.h b/src/libtrx/include/libtrx/gfx/gl/program.h
index 427a8bb4d..0ab22dae7 100644
--- a/src/libtrx/include/libtrx/gfx/gl/program.h
+++ b/src/libtrx/include/libtrx/gfx/gl/program.h
@@ -6,6 +6,7 @@
 #include <stdbool.h>
 
 typedef struct {
+    bool initialized;
     GLuint id;
 } GFX_GL_PROGRAM;
 
diff --git a/src/libtrx/include/libtrx/gfx/gl/sampler.h b/src/libtrx/include/libtrx/gfx/gl/sampler.h
index b1bae2ae1..e45e6c29a 100644
--- a/src/libtrx/include/libtrx/gfx/gl/sampler.h
+++ b/src/libtrx/include/libtrx/gfx/gl/sampler.h
@@ -2,7 +2,10 @@
 
 #include "../gl/gl_core_3_3.h"
 
+#include <stdbool.h>
+
 typedef struct {
+    bool initialized;
     GLuint id;
 } GFX_GL_SAMPLER;
 
diff --git a/src/libtrx/include/libtrx/gfx/gl/texture.h b/src/libtrx/include/libtrx/gfx/gl/texture.h
index 96b7bc34e..99d7b1543 100644
--- a/src/libtrx/include/libtrx/gfx/gl/texture.h
+++ b/src/libtrx/include/libtrx/gfx/gl/texture.h
@@ -2,7 +2,10 @@
 
 #include "../gl/gl_core_3_3.h"
 
+#include <stdbool.h>
+
 typedef struct {
+    bool initialized;
     GLuint id;
     GLenum target;
 } GFX_GL_TEXTURE;
diff --git a/src/libtrx/include/libtrx/gfx/gl/vertex_array.h b/src/libtrx/include/libtrx/gfx/gl/vertex_array.h
index 01615f1fc..e25b26481 100644
--- a/src/libtrx/include/libtrx/gfx/gl/vertex_array.h
+++ b/src/libtrx/include/libtrx/gfx/gl/vertex_array.h
@@ -2,7 +2,10 @@
 
 #include "../gl/gl_core_3_3.h"
 
+#include <stdbool.h>
+
 typedef struct {
+    bool initialized;
     GLuint id;
 } GFX_GL_VERTEX_ARRAY;