diff --git a/libguile/smob.c b/libguile/smob.c
index 1911460cf..215bb5913 100644
--- a/libguile/smob.c
+++ b/libguile/smob.c
@@ -454,7 +454,7 @@ scm_i_new_double_smob (scm_t_bits tc, scm_t_bits data1,
    SCM_NEWSMOB and are no longer used.  They are still here to preserve
    ABI stability in the 2.0 series.  */
 void
-scm_i_finalize_smob (GC_PTR ptr, GC_PTR data)
+scm_i_finalize_smob (void *ptr, void *data)
 {
   finalize_smob (ptr, data);
 }
diff --git a/libguile/smob.h b/libguile/smob.h
index d4b7c6cea..60abe3733 100644
--- a/libguile/smob.h
+++ b/libguile/smob.h
@@ -76,7 +76,7 @@ SCM_INLINE SCM scm_new_double_smob (scm_t_bits tc, scm_t_bits,
 /* These two are internal details of the previous implementation of
    SCM_NEWSMOB and are no longer used.  They are still here to preserve
    ABI stability in the 2.0 series.  */
-SCM_API void scm_i_finalize_smob (GC_PTR ptr, GC_PTR data);
+SCM_API void scm_i_finalize_smob (void *ptr, void *data);
 SCM_API SCM scm_i_new_smob_with_mark_proc (scm_t_bits tc, scm_t_bits,
                                            scm_t_bits, scm_t_bits);