diff --git a/libguile/async.h b/libguile/async.h
index ba6c77c9b..f666437ed 100644
--- a/libguile/async.h
+++ b/libguile/async.h
@@ -29,10 +29,6 @@
 
 
 
-#define scm_mask_ints (SCM_I_CURRENT_THREAD->block_asyncs != 0)
-
-
-
 SCM_API void scm_async_click (void);
 SCM_API void scm_switch (void);
 SCM_API SCM scm_async (SCM thunk);
diff --git a/libguile/deprecated.c b/libguile/deprecated.c
index a8aebeeee..df7ba4dc6 100644
--- a/libguile/deprecated.c
+++ b/libguile/deprecated.c
@@ -1467,6 +1467,14 @@ scm_i_defer_ints_etc ()
      "Use a mutex instead if appropriate.");
 }
 
+int
+scm_i_mask_ints (void)
+{
+  scm_c_issue_deprecation_warning ("`scm_mask_ints' is deprecated.");
+  return (SCM_I_CURRENT_THREAD->block_asyncs != 0);
+}
+
+
 SCM
 scm_guard (SCM guardian, SCM obj, int throw_p)
 {
diff --git a/libguile/deprecated.h b/libguile/deprecated.h
index 93738f1c0..ed1a105ee 100644
--- a/libguile/deprecated.h
+++ b/libguile/deprecated.h
@@ -576,6 +576,12 @@ SCM_DEPRECATED void scm_i_defer_ints_etc (void);
 #define SCM_REDEFER_INTS scm_i_defer_ints_etc ()
 #define SCM_REALLOW_INTS scm_i_defer_ints_etc ()
 
+/* In the old days (pre-1.8), this macro was sometimes used as an lvalue as
+   in "scm_mask_ints = 1" to block async execution.  It no longer works.  */
+#define scm_mask_ints (scm_i_mask_ints ())
+
+SCM_DEPRECATED int scm_i_mask_ints (void);
+
 /* Deprecated since they are unnecessary and had not been documented.
  */
 SCM_DEPRECATED SCM scm_guard (SCM guardian, SCM obj, int throw_p);