diff --git a/ChangeLog b/ChangeLog
index 8dc1ce24e..7a4e3b244 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2015-03-21  Alexei Podtelezhnikov <apodtele@gmail.com>
+
+	[base] Optimize `FT_Angle_Diff'.
+
+	Under normal circumstances we are usually close to the desired range
+	of angle values, so that the remainder is not really necessary.
+
+	* src/base/fttrigon.c (FT_Angle_Diff): Use loops instead of remainder.
+
+	* src/autofit/aftypes.h (AF_ANGLE_DIFF): Ditto in the unused macro.
+
 2015-03-21  Werner Lemberg  <wl@gnu.org>
 
 	[truetype] Improve `gvar' handling.
diff --git a/src/autofit/aftypes.h b/src/autofit/aftypes.h
index 1666674af..e105dc83d 100644
--- a/src/autofit/aftypes.h
+++ b/src/autofit/aftypes.h
@@ -138,11 +138,10 @@ extern void*  _af_debug_hints;
     AF_Angle  _delta = (angle2) - (angle1);     \
                                                 \
                                                 \
-    _delta %= AF_ANGLE_2PI;                     \
-    if ( _delta < 0 )                           \
+    while ( _delta <= -AF_ANGLE_PI )            \
       _delta += AF_ANGLE_2PI;                   \
                                                 \
-    if ( _delta > AF_ANGLE_PI )                 \
+    while ( _delta > AF_ANGLE_PI )              \
       _delta -= AF_ANGLE_2PI;                   \
                                                 \
     result = _delta;                            \
diff --git a/src/base/fttrigon.c b/src/base/fttrigon.c
index 42552459c..5b24304c2 100644
--- a/src/base/fttrigon.c
+++ b/src/base/fttrigon.c
@@ -512,11 +512,10 @@
     FT_Angle  delta = angle2 - angle1;
 
 
-    delta %= FT_ANGLE_2PI;
-    if ( delta < 0 )
+    while ( delta <= -FT_ANGLE_PI )
       delta += FT_ANGLE_2PI;
 
-    if ( delta > FT_ANGLE_PI )
+    while ( delta > FT_ANGLE_PI )
       delta -= FT_ANGLE_2PI;
 
     return delta;