diff --git a/lib/arm/instructions/stack_instruction.rb b/lib/arm/instructions/stack_instruction.rb
index f10737f9..93cf16e4 100644
--- a/lib/arm/instructions/stack_instruction.rb
+++ b/lib/arm/instructions/stack_instruction.rb
@@ -1,11 +1,11 @@
 module Arm
   # ADDRESSING MODE 4
-  
+
   class StackInstruction < Instruction
     include Arm::Constants
 
     def initialize(first , attributes)
-      super(attributes) 
+      super(attributes)
       @first = first
       @attributes[:update_status] = 0 if @attributes[:update_status] == nil
       @attributes[:condition_code] = :al if @attributes[:condition_code] == nil
@@ -17,16 +17,16 @@ module Arm
       # downward growing, decrement before memory access
       # official ARM style stack as used by gas
     end
-                  
+
     def assemble(io)
       # don't overwrite instance variables, to make assembly repeatable
       operand = @operand
-      
+
       if (@first.is_a?(Array))
         operand = 0
         @first.each do |r|
           raise "nil register in push, index #{r}- #{inspect}" if r.nil?
-          operand |= (1 << reg_code(r))
+          operand = operand | (1 << reg_code(r))
         end
       else
         raise "invalid operand argument #{inspect}"
@@ -46,14 +46,14 @@ module Arm
       @rn = :sp # sp register
       #assemble of old
       val = operand
-      val |= (reg_code(@rn) <<             16)
-      val |= (is_pop <<              16+4) #20
-      val |= (write_base <<          16+4+ 1) 
-      val |= (@attributes[:update_status] <<  16+4+ 1+1) 
-      val |= (up_down <<             16+4+ 1+1+1)
-      val |= (pre_post_index <<      16+4+ 1+1+1+1)#24
-      val |= (instuction_class <<    16+4+ 1+1+1+1 +2) 
-      val |= (cond <<                16+4+ 1+1+1+1 +2+2)
+      val = val | (reg_code(@rn) <<             16)
+      val = val | (is_pop <<              16+4) #20
+      val = val | (write_base <<          16+4+ 1)
+      val = val | (@attributes[:update_status] <<  16+4+ 1+1)
+      val = val | (up_down <<             16+4+ 1+1+1)
+      val = val | (pre_post_index <<      16+4+ 1+1+1+1)#24
+      val = val | (instuction_class <<    16+4+ 1+1+1+1 +2)
+      val = val | (cond <<                16+4+ 1+1+1+1 +2+2)
       io.write_uint32 val
     end
 
@@ -76,5 +76,5 @@ module Arm
       "#{opcode} [#{@first.collect {|f| f.to_asm}.join(',') }] #{super}"
     end
   end
-  
-end
\ No newline at end of file
+
+end