diff --git a/helgrind/hg_errors.c b/helgrind/hg_errors.c
index 1d1acc2..8a7ebe1 100644
--- a/helgrind/hg_errors.c
+++ b/helgrind/hg_errors.c
@@ -1006,7 +1006,7 @@
 #  undef TRY
 }
 
-Bool HG_(read_extra_suppression_info) ( Int fd, Char* buf, Int nBuf,
+Bool HG_(read_extra_suppression_info) ( Int fd, Char** bufpp, SizeT* nBufp,
                                         Supp* su )
 {
    /* do nothing -- no extra suppression info present.  Return True to
diff --git a/helgrind/hg_errors.h b/helgrind/hg_errors.h
index 9bb6502..9760b92 100644
--- a/helgrind/hg_errors.h
+++ b/helgrind/hg_errors.h
@@ -40,7 +40,7 @@
 void  HG_(pp_Error)        ( Error* err );
 UInt  HG_(update_extra)    ( Error* err );
 Bool  HG_(recognised_suppression) ( Char* name, Supp *su );
-Bool  HG_(read_extra_suppression_info) ( Int fd, Char* buf, Int nBuf,
+Bool  HG_(read_extra_suppression_info) ( Int fd, Char** bufpp, SizeT* nBufp,
                                          Supp* su );
 Bool  HG_(error_matches_suppression) ( Error* err, Supp* su );
 Char* HG_(get_error_name) ( Error* err );