diff --git a/amiga/bitmap.c b/amiga/bitmap.c
index e28000aa4..47c3ca9fe 100644
--- a/amiga/bitmap.c
+++ b/amiga/bitmap.c
@@ -208,14 +208,17 @@ int bitmap_get_height(void *bitmap)
 	}
 }
 
-size_t bitmap_get_bpp(void *bitmap)
+
+/**
+ * Find the bytes per pixel of a bitmap
+ *
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
+ * \return bytes per pixel
+ */
+
+size_t bitmap_get_bpp(void *vbitmap)
 {
-	if(bitmap)
-	{
-		return 32;
-	}
-	else
-	{
-		return 0;
-	}
+	struct bitmap *bitmap = (struct bitmap *)vbitmap;
+	assert(bitmap);
+	return 4;
 }
diff --git a/beos/beos_bitmap.cpp b/beos/beos_bitmap.cpp
index 778a2eb68..06e686c0e 100644
--- a/beos/beos_bitmap.cpp
+++ b/beos/beos_bitmap.cpp
@@ -151,8 +151,8 @@ void *bitmap_create(int width, int height, unsigned int state)
 /**
  * Sets whether a bitmap should be plotted opaque
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
- * \param  opaque  whether the bitmap should be plotted opaque
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
+ * \param  opaque   whether the bitmap should be plotted opaque
  */
 void bitmap_set_opaque(void *vbitmap, bool opaque)
 {
@@ -166,8 +166,8 @@ void bitmap_set_opaque(void *vbitmap, bool opaque)
 /**
  * Tests whether a bitmap has an opaque alpha channel
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
- * \return whether the bitmap is opaque
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
+ * \return whether  the bitmap is opaque
  */
 bool bitmap_test_opaque(void *vbitmap)
 {
@@ -181,7 +181,7 @@ bool bitmap_test_opaque(void *vbitmap)
 /**
  * Gets whether a bitmap should be plotted opaque
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  */
 bool bitmap_get_opaque(void *vbitmap)
 {
@@ -195,7 +195,7 @@ bool bitmap_get_opaque(void *vbitmap)
 /**
  * Return a pointer to the pixel data in a bitmap.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return pointer to the pixel buffer
  *
  * The pixel data is packed as BITMAP_FORMAT, possibly with padding at the end
@@ -213,7 +213,7 @@ unsigned char *bitmap_get_buffer(void *vbitmap)
 /**
  * Find the width of a pixel row in bytes.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return width of a pixel row in the bitmap
  */
 
@@ -228,7 +228,7 @@ size_t bitmap_get_rowstride(void *vbitmap)
 /**
  * Find the bytes per pixels of a bitmap.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return bytes per pixels of the bitmap
  */
 
@@ -253,7 +253,7 @@ nsbeos_bitmap_free_pretiles(struct bitmap *bitmap)
 /**
  * Free a bitmap.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  */
 
 void bitmap_destroy(void *vbitmap)
@@ -270,9 +270,9 @@ void bitmap_destroy(void *vbitmap)
 /**
  * Save a bitmap in the platform's native format.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
- * \param  path    pathname for file
- * \param  flags   modify the behaviour of the save
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
+ * \param  path     pathname for file
+ * \param  flags    modify the behaviour of the save
  * \return true on success, false on error and error reported
  */
 
@@ -297,14 +297,14 @@ bool bitmap_save(void *vbitmap, const char *path, unsigned flags)
 /**
  * The bitmap image has changed, so flush any persistant cache.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  */
 void bitmap_modified(void *vbitmap) {
 	struct bitmap *bitmap = (struct bitmap *)vbitmap;
 	// convert the shadow (ABGR) to into the primary bitmap
-	nsbeos_rgba_to_bgra(bitmap->shadow->Bits(), bitmap->primary->Bits(), 
-		bitmap->primary->Bounds().Width() + 1, 
-		bitmap->primary->Bounds().Height() + 1, 
+	nsbeos_rgba_to_bgra(bitmap->shadow->Bits(), bitmap->primary->Bits(),
+		bitmap->primary->Bounds().Width() + 1,
+		bitmap->primary->Bounds().Height() + 1,
 		bitmap->primary->BytesPerRow());
 	nsbeos_bitmap_free_pretiles(bitmap);
 }
@@ -313,7 +313,7 @@ void bitmap_modified(void *vbitmap) {
 /**
  * The bitmap image can be suspended.
  *
- * \param  bitmap  	a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  	a bitmap, as returned by bitmap_create()
  * \param  private_word	a private word to be returned later
  * \param  suspend	the function to be called upon suspension
  * \param  resume	the function to be called when resuming
diff --git a/gtk/gtk_bitmap.c b/gtk/gtk_bitmap.c
index e08741260..0fc0414e9 100644
--- a/gtk/gtk_bitmap.c
+++ b/gtk/gtk_bitmap.c
@@ -73,8 +73,8 @@ void *bitmap_create(int width, int height, unsigned int state)
 /**
  * Sets whether a bitmap should be plotted opaque
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
- * \param  opaque  whether the bitmap should be plotted opaque
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
+ * \param  opaque   whether the bitmap should be plotted opaque
  */
 void bitmap_set_opaque(void *vbitmap, bool opaque)
 {
@@ -87,7 +87,7 @@ void bitmap_set_opaque(void *vbitmap, bool opaque)
 /**
  * Tests whether a bitmap has an opaque alpha channel
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return whether the bitmap is opaque
  */
 bool bitmap_test_opaque(void *vbitmap)
@@ -102,7 +102,7 @@ bool bitmap_test_opaque(void *vbitmap)
 /**
  * Gets whether a bitmap should be plotted opaque
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  */
 bool bitmap_get_opaque(void *vbitmap)
 {
@@ -116,7 +116,7 @@ bool bitmap_get_opaque(void *vbitmap)
 /**
  * Return a pointer to the pixel data in a bitmap.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return pointer to the pixel buffer
  *
  * The pixel data is packed as BITMAP_FORMAT, possibly with padding at the end
@@ -134,7 +134,7 @@ unsigned char *bitmap_get_buffer(void *vbitmap)
 /**
  * Find the width of a pixel row in bytes.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return width of a pixel row in the bitmap
  */
 
@@ -149,7 +149,7 @@ size_t bitmap_get_rowstride(void *vbitmap)
 /**
  * Find the bytes per pixel of a bitmap
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return bytes per pixel
  */
 
@@ -174,7 +174,7 @@ gtk_bitmap_free_pretiles(struct bitmap *bitmap)
 /**
  * Free a bitmap.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  */
 
 void bitmap_destroy(void *vbitmap)
@@ -190,9 +190,9 @@ void bitmap_destroy(void *vbitmap)
 /**
  * Save a bitmap in the platform's native format.
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
- * \param  path    pathname for file
- * \param  flags   modify the behaviour of the save
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
+ * \param  path     pathname for file
+ * \param  flags    modify the behaviour of the save
  * \return true on success, false on error and error reported
  */
 
diff --git a/riscos/bitmap.c b/riscos/bitmap.c
index dd1271f2e..902157128 100644
--- a/riscos/bitmap.c
+++ b/riscos/bitmap.c
@@ -1179,7 +1179,7 @@ int bitmap_get_height(void *vbitmap)
 /**
  * Find the bytes per pixel of a bitmap
  *
- * \param  bitmap  a bitmap, as returned by bitmap_create()
+ * \param  vbitmap  a bitmap, as returned by bitmap_create()
  * \return bytes per pixel
  */