diff --git a/test/effects.js b/test/effects.js
index 247fec6..a8f15c6 100644
--- a/test/effects.js
+++ b/test/effects.js
@@ -152,3 +152,51 @@ exports['test 4xy vibrato'] = function(assert) {
   assert.equal(p.toFixed(3), "-1.546", 'row 5 tick 1 period -1.546');
 };
 
+exports['test Axy volume slide'] = function(assert) {
+  var xm = testdata.resetXMData();
+  XMPlayer.xm.tempo = 6;
+
+  xm.patterns[0] = [
+    [[48,  1, -1, 10, 0x0f]],  // C-4  1 -- A0f (slide down)
+    [[-1, -1, -1, 10, 0x90]],  // --- -- -- A90 (slide up)
+    [[-1, -1, -1, 10, 0x00]],  // --- -- -- A00 (continue same)
+    [[-1, -1, 0x30, 10, 0x11]],  // --- -- 20 A11 (invalid, do nothing)
+  ];
+  var ch = xm.channelinfo[0];
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 64, 'row 0 tick 0 vol 64');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 49, 'row 0 tick 1 vol 49');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 34, 'row 0 tick 2 vol 34');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 19, 'row 0 tick 3 vol 19');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 4, 'row 0 tick 4 vol 4');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 0, 'row 0 tick 5 vol 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 0, 'row 1 tick 0 vol 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.vol, 9, 'row 1 tick 1 vol 9');
+  XMPlayer.nextTick();  // row 1 tick 2
+  XMPlayer.nextTick();  // tick 3
+  XMPlayer.nextTick();  // tick 4
+  XMPlayer.nextTick();  // tick 5
+  assert.equal(ch.vol, 45, 'row 1 tick 5 vol 45');
+  XMPlayer.nextTick();  // row 2 tick 0
+  assert.equal(ch.vol, 45, 'row 2 tick 0 vol 45');
+  XMPlayer.nextTick();  // row 2 tick 1
+  assert.equal(ch.vol, 54, 'row 2 tick 1 vol 54');
+  XMPlayer.nextTick();  // tick 2
+  XMPlayer.nextTick();  // tick 3
+  assert.equal(ch.vol, 64, 'row 2 tick 3 vol 64');
+  XMPlayer.nextTick();  // tick 4
+  XMPlayer.nextTick();  // tick 5
+  XMPlayer.nextTick();  // row 3 tick 0
+  assert.equal(ch.vol, 32, 'row 3 tick 0 vol 32');
+  XMPlayer.nextTick();  // tick 1
+  assert.equal(ch.vol, 32, 'row 3 tick 1 vol 32');
+  XMPlayer.nextTick();  // tick 2
+  assert.equal(ch.vol, 32, 'row 3 tick 2 vol 32');
+};
diff --git a/test/testdata.js b/test/testdata.js
index 0ca0568..8157cd9 100644
--- a/test/testdata.js
+++ b/test/testdata.js
@@ -52,6 +52,6 @@ exports.resetXMData = function() {
   // reset song position
   XMPlayer.cur_songpos = -1;
   XMPlayer.cur_pat = -1;
-  XMPlayer.cur_tick = xm.tempo;
+  XMPlayer.cur_tick = 64;
   return xm;
 };
diff --git a/xmeffects.js b/xmeffects.js
index 5832d3d..6c27a99 100644
--- a/xmeffects.js
+++ b/xmeffects.js
@@ -95,11 +95,7 @@ function eff_t0_9(ch, data) {  // sample offset
 
 function eff_t0_a(ch, data) {  // volume slide
   if (data) {
-    if (data & 0x0f) {
-      ch.volumeslide = -(data & 0x0f);
-    } else {
-      ch.volumeslide = data >> 4;
-    }
+    ch.volumeslide = -(data & 0x0f) + (data >> 4);
   }
 }