diff --git a/ChangeLog b/ChangeLog
index 6026a5979..0a29b61a6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,16 @@
 	* src/autofit/aflatin.c (af_latin_metrics_scale_dim): Fix change
 	from 2011-05-04.
 
+2011-06-19  suzuki toshiya  <mpsuzuki@hiroshima-u.ac.jp>
+
+	[gxvalid] make the `prop' validation tracing verbose.
+
+	* src/gxvalid/gxvprop.c: Add tracing messages for errors.
+
+2011-06-19  suzuki toshiya  <mpsuzuki@hiroshima-u.ac.jp>
+
+	[autogen.sh] Reflect environment variable LIBTOOLIZE.
+
 2011-06-18  Werner Lemberg <wl@gnu.org>
 
 	Update license documentation.
diff --git a/autogen.sh b/autogen.sh
index c28a51c13..9f2fb6a3e 100644
--- a/autogen.sh
+++ b/autogen.sh
@@ -118,9 +118,12 @@ fi
 
 # On MacOS X, the GNU libtool is named `glibtool'.
 HOSTOS=`uname`
-LIBTOOLIZE=libtoolize
-if test "$HOSTOS"x = Darwinx; then
+if test "$LIBTOOLIZE"x != x; then
+  :
+elif test "$HOSTOS"x = Darwinx; then
   LIBTOOLIZE=glibtoolize
+else
+  LIBTOOLIZE=libtoolize
 fi
 
 if test "$ACLOCAL"x = x; then
diff --git a/src/gxvalid/gxvprop.c b/src/gxvalid/gxvprop.c
index 66c3ab740..54777271a 100644
--- a/src/gxvalid/gxvprop.c
+++ b/src/gxvalid/gxvprop.c
@@ -96,7 +96,10 @@
 
     if ( glyph->advance.x != (FT_Pos)0 ||
          glyph->advance.y != (FT_Pos)0 )
+    {
+      GXV_TRACE(( "  found non-zero advance in zero-advance glyph\n" ));
       FT_INVALID_DATA;
+    }
 
     GXV_EXIT;
   }
@@ -119,7 +122,10 @@
 
       offset = (FT_UShort)( property & GXV_PROP_COMPLEMENTARY_BRACKET_OFFSET );
       if ( offset == 0 )
-        FT_INVALID_DATA;
+      {
+        GXV_TRACE(( "  found zero offset to property\n" ));
+        FT_INVALID_OFFSET;
+      }
 
       complement = (char)( offset >> 8 );
       if ( complement & 0x08 )
@@ -131,7 +137,10 @@
 
         /* The gid for complement must be greater than 0 */
         if ( glyph <= complement )
+        {
+          GXV_TRACE(( "  found non-positive glyph complement\n" ));
           FT_INVALID_DATA;
+        }
       }
       else
       {
@@ -150,18 +159,27 @@
     if ( property & GXV_PROP_ATTACHING_TO_RIGHT )
     {
       if ( GXV_PROP_DATA( version ) == 0x00010000UL )
+      {
+        GXV_TRACE(( "  found older version (1.0) in new version table\n" ));
         FT_INVALID_DATA;
+      }
     }
 
     if ( property & GXV_PROP_RESERVED )
+    {
+      GXV_TRACE(( "  found non-zero bits in reserved bits\n" ));
       FT_INVALID_DATA;
+    }
 
     if ( ( property & GXV_PROP_DIRECTIONALITY_CLASS ) > 11 )
     {
       /* TODO: Too restricted. Use the validation level. */
       if ( GXV_PROP_DATA( version ) == 0x00010000UL ||
            GXV_PROP_DATA( version ) == 0x00020000UL )
+      {
+        GXV_TRACE(( "  found too old version in directionality class\n" ));
         FT_INVALID_DATA;
+      }
     }
   }
 
@@ -264,16 +282,26 @@
     format      = FT_NEXT_USHORT( p );
     defaultProp = FT_NEXT_USHORT( p );
 
+    GXV_TRACE(( "  version 0x%08x\n", version ));
+    GXV_TRACE(( "  format  0x%04x\n", format ));
+    GXV_TRACE(( "  defaultProp  0x%04x\n", defaultProp ));
+
     /* only versions 1.0, 2.0, 3.0 are defined (1996) */
     if ( version != 0x00010000UL &&
          version != 0x00020000UL &&
          version != 0x00030000UL )
+    {
+      GXV_TRACE(( "  found unknown version\n" ));
       FT_INVALID_FORMAT;
+    }
 
 
     /* only formats 0x0000, 0x0001 are defined (1996) */
     if ( format > 1 )
+    {
+      GXV_TRACE(( "  found unknown format\n" ));
       FT_INVALID_FORMAT;
+    }
 
     gxv_prop_property_validate( defaultProp, 0, valid );