diff --git a/ChangeLog b/ChangeLog
index f9cf6381..01c05564 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
  * src/msgwindow.c:
    Fix a segfault after clicking on a messages window Find Usage item
    after the relevant document has been closed.
+ * src/msgwindow.c, src/document.h:
+   Move DOC_VALID() macro to document.h, add dox.
 
 
 2008-06-12  Enrico Tröger  <enrico(dot)troeger(at)uvena(dot)de>
diff --git a/src/document.h b/src/document.h
index b2c35a8c..b6be7e58 100644
--- a/src/document.h
+++ b/src/document.h
@@ -130,6 +130,14 @@ extern GPtrArray *documents_array;
  **/
 #define documents ((GeanyDocument **)documents_array->pdata)
 
+/** Check that the @a doc_ptr document still exists (has not been closed).
+ * This is useful when @a doc_ptr was stored some time earlier and documents may have been
+ * closed since then.
+ * @note This should not be used to check the result of the main API functions,
+ * these only need a NULL-pointer check - @c p_document->get_current() != @c NULL. */
+#define DOC_VALID(doc_ptr) \
+	((doc_ptr) != NULL && (doc_ptr)->is_valid)
+
 /** NULL-safe way to get the index of @a doc_ptr in the documents array. */
 #define DOC_IDX(doc_ptr) \
 	(doc_ptr ? doc_ptr->index : -1)
diff --git a/src/msgwindow.c b/src/msgwindow.c
index 3126d488..f7ddcd8c 100644
--- a/src/msgwindow.c
+++ b/src/msgwindow.c
@@ -791,9 +791,6 @@ void msgwin_parse_compiler_error_line(const gchar *string, const gchar *dir, gch
 }
 
 
-#define DOC_VALID(doc_ptr) \
-	((doc_ptr) != NULL && (doc_ptr)->is_valid)
-
 gboolean msgwin_goto_messages_file_line()
 {
 	GtkTreeIter iter;