diff --git a/libguile/ChangeLog b/libguile/ChangeLog
index 92aea05b9..d1f2dfd6f 100644
--- a/libguile/ChangeLog
+++ b/libguile/ChangeLog
@@ -1,3 +1,7 @@
+2001-10-12  Mikael Djurfeldt  <mdj@linnaeus>
+
+	* validate.h (SCM_VALIDATE_DOUBLE_DEF_COPY): New macro.
+	
 2001-10-08  Rob Browning  <rlb@defaultvalue.org>
 
 	* gc.c: support ia64 register backing store.
diff --git a/libguile/validate.h b/libguile/validate.h
index ba807c6a1..43e877ff8 100644
--- a/libguile/validate.h
+++ b/libguile/validate.h
@@ -289,6 +289,19 @@
       } \
   } while (0)
 
+#define SCM_VALIDATE_DOUBLE_DEF_COPY(pos, k, default, cvar) \
+  do { \
+    if (SCM_UNBNDP (k)) \
+      { \
+        k = scm_make_real (default); \
+        cvar = default; \
+      } \
+    else \
+      { \
+        cvar = SCM_NUM2DOUBLE (pos, k); \
+      } \
+  } while (0)
+
 /* [low,high) */
 #define SCM_VALIDATE_INUM_RANGE(pos,k,low,high) \
   do { SCM_ASSERT(SCM_INUMP(k), k, pos, FUNC_NAME); \