diff --git a/ChangeLog b/ChangeLog
index 0c1f2a0fa..d8613e5af 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2018-08-30  Werner Lemberg  <wl@gnu.org>
+
+	[autofit] Trace `before' and `after' edges of strong points.
+
+	* src/autofit/afhints.h (AF_PointRec) [FT_DEBUG_AUTOFIT]: New arrays
+	`before' and `after'.
+
+	* src/autofit/afhints.c (af_get_strong_edge_index): New auxiliary
+	function.
+	(af_glyph_hints_dump_points): Trace `before' and `after' edges.
+	(af_glyph_hints_align_strong_points) [FT_DEBUG_AUTOFIT]: Set
+	`before' and `after' information.
+
 2018-08-30  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	[base] Overflow-resistant bitmap presetting.
diff --git a/src/autofit/afhints.c b/src/autofit/afhints.c
index 171ceb818..660587fdf 100644
--- a/src/autofit/afhints.c
+++ b/src/autofit/afhints.c
@@ -297,6 +297,19 @@
   }
 
 
+  static int
+  af_get_strong_edge_index( AF_GlyphHints  hints,
+                            AF_Edge*       strong_edges,
+                            int            dimension )
+  {
+    AF_AxisHints  axis  = &hints->axis[dimension];
+    AF_Edge       edges = axis->edges;
+
+
+    return AF_INDEX_NUM( strong_edges[dimension], edges );
+  }
+
+
 #ifdef __cplusplus
   extern "C" {
 #endif
@@ -317,8 +330,10 @@
     {
       AF_DUMP(( "  index  hedge  hseg  vedge  vseg  flags "
              /* "  XXXXX  XXXXX XXXXX  XXXXX XXXXX  XXXXXX" */
-                "  xorg  yorg  xscale  yscale   xfit    yfit" ));
+                "  xorg  yorg  xscale  yscale   xfit    yfit "
              /* " XXXXX XXXXX XXXX.XX XXXX.XX XXXX.XX XXXX.XX" */
+                "  hbef  haft  vbef  vaft" ));
+             /* " XXXXX XXXXX XXXXX XXXXX" */
     }
     else
       AF_DUMP(( "  (none)\n" ));
@@ -330,6 +345,7 @@
       int  segment_idx_1 = af_get_segment_index( hints, point_idx, 1 );
 
       char  buf1[16], buf2[16], buf3[16], buf4[16];
+      char  buf5[16], buf6[16], buf7[16], buf8[16];
 
 
       /* insert extra newline at the beginning of a contour */
@@ -340,7 +356,8 @@
       }
 
       AF_DUMP(( "  %5d  %5s %5s  %5s %5s  %s"
-                " %5d %5d %7.2f %7.2f %7.2f %7.2f\n",
+                " %5d %5d %7.2f %7.2f %7.2f %7.2f"
+                " %5s %5s %5s %5s\n",
                 point_idx,
                 af_print_idx( buf1,
                               af_get_edge_index( hints, segment_idx_1, 1 ) ),
@@ -359,7 +376,20 @@
                 point->ox / 64.0,
                 point->oy / 64.0,
                 point->x / 64.0,
-                point->y / 64.0 ));
+                point->y / 64.0,
+
+                af_print_idx( buf5, af_get_strong_edge_index( hints,
+                                                              point->before,
+                                                              1 ) ),
+                af_print_idx( buf6, af_get_strong_edge_index( hints,
+                                                              point->after,
+                                                              1 ) ),
+                af_print_idx( buf7, af_get_strong_edge_index( hints,
+                                                              point->before,
+                                                              0 ) ),
+                af_print_idx( buf8, af_get_strong_edge_index( hints,
+                                                              point->after,
+                                                              0 ) ) ));
     }
     AF_DUMP(( "\n" ));
   }
@@ -1309,6 +1339,12 @@
         if ( delta >= 0 )
         {
           u = edge->pos - ( edge->opos - ou );
+
+#ifdef FT_DEBUG_AUTOFIT
+          point->before[dim] = edge;
+          point->after[dim]  = NULL;
+#endif
+
           goto Store_Point;
         }
 
@@ -1318,6 +1354,12 @@
         if ( delta >= 0 )
         {
           u = edge->pos + ( ou - edge->opos );
+
+#ifdef FT_DEBUG_AUTOFIT
+          point->before[dim] = NULL;
+          point->after[dim]  = edge;
+#endif
+
           goto Store_Point;
         }
 
@@ -1364,6 +1406,12 @@
             {
               /* we are on the edge */
               u = edge->pos;
+
+#ifdef FT_DEBUG_AUTOFIT
+              point->before[dim] = NULL;
+              point->after[dim]  = NULL;
+#endif
+
               goto Store_Point;
             }
           }
@@ -1374,6 +1422,11 @@
             AF_Edge  after  = edges + min + 0;
 
 
+#ifdef FT_DEBUG_AUTOFIT
+            point->before[dim] = before;
+            point->after[dim]  = after;
+#endif
+
             /* assert( before && after && before != after ) */
             if ( before->scale == 0 )
               before->scale = FT_DivFix( after->pos - before->pos,
diff --git a/src/autofit/afhints.h b/src/autofit/afhints.h
index aee9d468f..5fb9741c4 100644
--- a/src/autofit/afhints.h
+++ b/src/autofit/afhints.h
@@ -252,6 +252,12 @@ FT_BEGIN_HEADER
     AF_Point   next;     /* next point in contour     */
     AF_Point   prev;     /* previous point in contour */
 
+#ifdef FT_DEBUG_AUTOFIT
+    /* track `before' and `after' edges for strong points */
+    AF_Edge    before[2];
+    AF_Edge    after[2];
+#endif
+
   } AF_PointRec;