diff --git a/include/mujoco/mjrender.h b/include/mujoco/mjrender.h
index 89c79f0e..8c68f230 100644
--- a/include/mujoco/mjrender.h
+++ b/include/mujoco/mjrender.h
@@ -108,7 +108,7 @@ struct mjrContext_ {              // custom OpenGL context
 
   // texture objects and info
   int ntexture;                   // number of allocated textures
-  int textureType[100];           // type of texture (mjtTexture)
+  int textureType[100];           // type of texture (mjtTexture) (ntexture)
   unsigned int texture[100];      // texture names
 
   // displaylist starting positions
@@ -129,10 +129,10 @@ struct mjrContext_ {              // custom OpenGL context
 
   // skin VBOs
   int nskin;                      // number of skins
-  unsigned int* skinvertVBO;      // skin vertex position VBOs
-  unsigned int* skinnormalVBO;    // skin vertex normal VBOs
-  unsigned int* skintexcoordVBO;  // skin vertex texture coordinate VBOs
-  unsigned int* skinfaceVBO;      // skin face index VBOs
+  unsigned int* skinvertVBO;      // skin vertex position VBOs (nskin)
+  unsigned int* skinnormalVBO;    // skin vertex normal VBOs (nskin)
+  unsigned int* skintexcoordVBO;  // skin vertex texture coordinate VBOs (nskin)
+  unsigned int* skinfaceVBO;      // skin face index VBOs (nskin)
 
   // character info
   int charWidth[127];             // character widths: normal and shadow
diff --git a/include/mujoco/mjvisualize.h b/include/mujoco/mjvisualize.h
index a3e99128..b11abb7e 100644
--- a/include/mujoco/mjvisualize.h
+++ b/include/mujoco/mjvisualize.h
@@ -268,20 +268,20 @@ struct mjvScene_ {                // abstract scene passed to OpenGL renderer
   // abstract geoms
   int      maxgeom;               // size of allocated geom buffer
   int      ngeom;                 // number of geoms currently in buffer
-  mjvGeom* geoms;                 // buffer for geoms
-  int*     geomorder;             // buffer for ordering geoms by distance to camera
+  mjvGeom* geoms;                 // buffer for geoms (ngeom)
+  int*     geomorder;             // buffer for ordering geoms by distance to camera (ngeom)
 
   // skin data
   int      nskin;                 // number of skins
-  int*     skinfacenum;           // number of faces in skin
-  int*     skinvertadr;           // address of skin vertices
-  int*     skinvertnum;           // number of vertices in skin
-  float*   skinvert;              // skin vertex data
-  float*   skinnormal;            // skin normal data
+  int*     skinfacenum;           // number of faces in skin (nskin)
+  int*     skinvertadr;           // address of skin vertices (nskin)
+  int*     skinvertnum;           // number of vertices in skin (nskin)
+  float*   skinvert;              // skin vertex data (nskin)
+  float*   skinnormal;            // skin normal data (nskin)
 
   // OpenGL lights
   int      nlight;                // number of lights currently in buffer
-  mjvLight lights[mjMAXLIGHT];    // buffer for lights
+  mjvLight lights[mjMAXLIGHT];    // buffer for lights (nlight)
 
   // OpenGL cameras
   mjvGLCamera camera[2];          // left and right camera