diff --git a/include/tgi.h b/include/tgi.h
index 2ef65b856..ecd98e6e8 100644
--- a/include/tgi.h
+++ b/include/tgi.h
@@ -141,15 +141,16 @@ unsigned char tgi_getmaxcolor (void);
 ** then be getmaxcolor()+1).
 */
 
-void __fastcall__ tgi_setcolor (unsigned char color);
-/* Set the current drawing color. */
+void __fastcall__ tgi_setcolor (unsigned char color_index);
+/* Set the current drawing color (palette index). */
 
 unsigned char tgi_getcolor (void);
-/* Return the current drawing color. */
+/* Return the current drawing color (palette index). */
 
 void __fastcall__ tgi_setpalette (const unsigned char* palette);
 /* Set the palette (not available with all drivers/hardware). palette is
-** a pointer to as many entries as there are colors.
+** a pointer to as many entries as there are colors required for the drivers
+** palette. This palette is the (only) place where to use the TGI_COLOR values.
 */
 
 const unsigned char* tgi_getpalette (void);
diff --git a/libsrc/apple2/tgi_colors.s b/libsrc/apple2/tgi_colors.s
index 53505b33d..936d89b76 100644
--- a/libsrc/apple2/tgi_colors.s
+++ b/libsrc/apple2/tgi_colors.s
@@ -1,6 +1,7 @@
 ;
 ; Target-specific black & white values for use by the target-shared TGI kernel
 ;
+; NOTE: These are indices into the default palette
 
         .include        "tgi-kernel.inc"
 
diff --git a/libsrc/common/tgi_colors.s b/libsrc/common/tgi_colors.s
index 6ef3729b4..ba14ffa09 100644
--- a/libsrc/common/tgi_colors.s
+++ b/libsrc/common/tgi_colors.s
@@ -1,6 +1,7 @@
 ;
 ; Target-specific black & white values for use by the target-shared TGI kernel
 ;
+; NOTE: These are indices into the default palette
 
         .include        "tgi-kernel.inc"
 
diff --git a/libsrc/lynx/tgi_colors.s b/libsrc/lynx/tgi_colors.s
index ebc8c2889..6d0ea442a 100644
--- a/libsrc/lynx/tgi_colors.s
+++ b/libsrc/lynx/tgi_colors.s
@@ -1,6 +1,7 @@
 ;
 ; Target-specific black & white values for use by the target-shared TGI kernel
 ;
+; NOTE: These are indices into the default palette
 
         .include        "tgi-kernel.inc"
 
diff --git a/libsrc/tgi/tgi-kernel.s b/libsrc/tgi/tgi-kernel.s
index cbd655279..c2d87b002 100644
--- a/libsrc/tgi/tgi-kernel.s
+++ b/libsrc/tgi/tgi-kernel.s
@@ -23,7 +23,7 @@ _tgi_error:         .res    1           ; Last error code
 _tgi_gmode:         .res    1           ; Flag: Graphics mode active
 _tgi_curx:          .res    2           ; Current drawing cursor X
 _tgi_cury:          .res    2           ; Current drawing cursor Y
-_tgi_color:         .res    1           ; Current drawing color
+_tgi_color:         .res    1           ; Current drawing color (palette index)
 _tgi_font:          .res    1           ; Which font to use
 _tgi_textdir:       .res    1           ; Current text direction
 _tgi_vectorfont:    .res    2           ; Pointer to vector font
diff --git a/libsrc/tgi/tgi_getcolor.s b/libsrc/tgi/tgi_getcolor.s
index c1c0022d0..95cf7d553 100644
--- a/libsrc/tgi/tgi_getcolor.s
+++ b/libsrc/tgi/tgi_getcolor.s
@@ -2,7 +2,7 @@
 ; Ullrich von Bassewitz, 22.06.2002
 ;
 ; unsigned char tgi_getcolor (void);
-; /* Return the current drawing color */
+; /* Return the current drawing color (palette index) */
 
 
         .include        "tgi-kernel.inc"
diff --git a/libsrc/tgi/tgi_setcolor.s b/libsrc/tgi/tgi_setcolor.s
index 16f075767..6f3bb1871 100644
--- a/libsrc/tgi/tgi_setcolor.s
+++ b/libsrc/tgi/tgi_setcolor.s
@@ -2,8 +2,8 @@
 ; 2002-06-21, Ullrich von Bassewitz
 ; 2020-06-04, Greg King
 ;
-; void __fastcall__ tgi_setcolor (unsigned char color);
-; /* Set the current drawing color */
+; void __fastcall__ tgi_setcolor (unsigned char color_index);
+; /* Set the current drawing color (palette index) */
 
 
         .include        "tgi-kernel.inc"