diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index d7fb84f576b..918b8af1dad 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,7 @@
+2011-10-24  Dodji Seketeli  <dodji@redhat.com>
+
+	* line-map.c (linemap_macro_map_lookup): Fix logic.
+
 2011-10-24  Dodji Seketeli  <dodji@redhat.com>
 
 	* include/line-map.h (linemap_expand_location): Take a line table
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index 7a1decc7501..23a0347cb5f 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -588,14 +588,14 @@ linemap_macro_map_lookup (struct line_maps *set, source_location line)
       mn = 0;
     }
 
-  do 
+  while (mn < mx)
     {
       md = (mx + mn) / 2;
       if (MAP_START_LOCATION (LINEMAPS_MACRO_MAP_AT (set, md)) > line)
-	mn = md;
+	mn = md + 1;
       else
 	mx = md;
-    } while (mx - mn > 1);
+    }
 
   LINEMAPS_MACRO_CACHE (set) = mx;
   result = LINEMAPS_MACRO_MAP_AT (set, LINEMAPS_MACRO_CACHE (set));