--- ../src-base/minecraft/net/minecraft/block/state/BlockPistonStructureHelper.java
+++ ../src-work/minecraft/net/minecraft/block/state/BlockPistonStructureHelper.java
@@ -80,7 +80,7 @@
     {
         Block block = this.field_177261_a.func_180495_p(p_177251_1_).func_177230_c();
 
-        if (block.func_149688_o() == Material.field_151579_a)
+        if (block.isAir(field_177261_a, p_177251_1_))
         {
             return true;
         }
@@ -111,7 +111,7 @@
                     BlockPos blockpos1 = p_177251_1_.func_177967_a(this.field_177257_d.func_176734_d(), i);
                     block = this.field_177261_a.func_180495_p(blockpos1).func_177230_c();
 
-                    if (block.func_149688_o() == Material.field_151579_a || !BlockPistonBase.func_180696_a(block, this.field_177261_a, blockpos1, this.field_177257_d, false) || blockpos1.equals(this.field_177259_b))
+                    if (block.isAir(field_177261_a, blockpos1)|| !BlockPistonBase.func_180696_a(block, this.field_177261_a, blockpos1, this.field_177257_d, false) || blockpos1.equals(this.field_177259_b))
                     {
                         break;
                     }
@@ -159,7 +159,7 @@
 
                     block = this.field_177261_a.func_180495_p(blockpos2).func_177230_c();
 
-                    if (block.func_149688_o() == Material.field_151579_a)
+                    if (block.isAir(field_177261_a, blockpos2))
                     {
                         return true;
                     }
