diff --git a/src/error.h b/src/error.h
index c155a1a..55cc82c 100644
--- a/src/error.h
+++ b/src/error.h
@@ -4,6 +4,7 @@
 
 #if __INCLUDE_LEVEL__ > 0
 #include <stdio.h>
+#include <stdlib.h>
 #endif
 
 #define ERROR_STR_PRE(v) #v
diff --git a/src/io/render.c b/src/io/render.c
index c6f4d2a..cdcf811 100644
--- a/src/io/render.c
+++ b/src/io/render.c
@@ -6,8 +6,6 @@
 
 #include <GLFW/glfw3.h>
 #include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
 
 #include "../error.h"
 #include "shader.h"
@@ -56,7 +54,7 @@ int render_init(void) {
 
 	// set VBO info
 	glBindBuffer(GL_ARRAY_BUFFER, vbo);
-	glEnableVertexAttribArray(0);
+	glEnableVertexAttribArray(0); // set the array data index to 0
 	glVertexAttribIPointer(0, 4, GL_INT, 4 * sizeof(int32_t), NULL);
 
 	glBindVertexArray(0);
diff --git a/src/util/conf.c b/src/util/conf.c
index ebb151c..094928d 100644
--- a/src/util/conf.c
+++ b/src/util/conf.c
@@ -9,7 +9,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/types.h>
 
 #include "../error.h"
 #include "atrb.h"