diff --git a/doc/ref/api-control.texi b/doc/ref/api-control.texi
index ae64514da..e778eb391 100644
--- a/doc/ref/api-control.texi
+++ b/doc/ref/api-control.texi
@@ -966,7 +966,9 @@ Guile) formats using @code{display} and @code{~S} (was
 @code{#f} depending on @var{key}: if @var{key} is
 @code{system-error} then it should be a list containing the
 Unix @code{errno} value; If @var{key} is @code{signal} then it
-should be a list containing the Unix signal number; otherwise
+should be a list containing the Unix signal number; If
+@var{key} is @code{out-of-range} or @code{wrong-type-arg},
+it is a list containing the bad value; otherwise
 it will usually be @code{#f}.
 @end deffn
 
diff --git a/doc/ref/api-debug.texi b/doc/ref/api-debug.texi
index cf4b2800a..adf40af61 100644
--- a/doc/ref/api-debug.texi
+++ b/doc/ref/api-debug.texi
@@ -23,10 +23,13 @@
 @node Interactive Debugging
 @subsection Interactive Debugging
 
-@deffn {Scheme Procedure} backtrace
+@deffn {Scheme Procedure} backtrace [highlights]
+@deffnx {C Function} scm_backtrace_with_highlights (highlights)
 @deffnx {C Function} scm_backtrace ()
 Display a backtrace of the stack saved by the last error
-to the current output port.
+to the current output port.  When @var{highlights} is given,
+it should be a list and all members of it are highligthed in
+the backtrace.
 @end deffn
 
 @deffn {Scheme Procedure} debug
@@ -246,13 +249,17 @@ Return the length of @var{stack}.
 Return the @var{index}'th frame from @var{stack}.
 @end deffn
 
-@deffn {Scheme Procedure} display-backtrace stack port [first [depth]]
+@deffn {Scheme Procedure} display-backtrace stack port [first [depth [highlights]]]
+@deffnx {C Function} scm_display_backtrace_with_highlights (stack, port, first, depth, highlights)
 @deffnx {C Function} scm_display_backtrace (stack, port, first, depth)
 Display a backtrace to the output port @var{port}. @var{stack}
 is the stack to take the backtrace from, @var{first} specifies
 where in the stack to start and @var{depth} how much frames
 to display. Both @var{first} and @var{depth} can be @code{#f},
 which means that default values will be used.
+When @var{highlights} is given,
+it should be a list and all members of it are highligthed in
+the backtrace.
 @end deffn