diff --git a/lib/asm/arm/builder_d.rb b/lib/asm/arm/builder_d.rb
index ff6ac4f0..6253b469 100644
--- a/lib/asm/arm/builder_d.rb
+++ b/lib/asm/arm/builder_d.rb
@@ -29,14 +29,16 @@ module Asm
 
       # Build representation for source value
       def build_operand(arg)
-        if (arg.is_a?(Asm::RegisterListArgNode))
+        if (arg.is_a?(Array))
           @operand = 0
-          arg.registers.each do |reg_node|
-            reg = reg_ref(reg_node)
+          arg.each do |sym , reg |
+            #allow an array of reg (strings), or the [:reg , name] produced by the instruction functions
+            reg = sym == :reg ? reg : sym
+            reg = reg_ref(reg)
             @operand |= (1 << reg)
           end
         else
-          raise Asm::AssemblyError.new(Asm::ERRSTR_INVALID_ARG, arg)
+          raise Asm::AssemblyError.new(Asm::ERRSTR_INVALID_ARG + " " + arg.inspect , arg)
         end
       end
 
diff --git a/lib/asm/arm/code_generator.rb b/lib/asm/arm/code_generator.rb
index 792d0d0f..6208cb7c 100644
--- a/lib/asm/arm/code_generator.rb
+++ b/lib/asm/arm/code_generator.rb
@@ -49,7 +49,8 @@ class Asm::Arm::CodeGenerator
     @asm.add_object Asm::Arm::Instruction.new(node)
   end
 
-  %w(adc add and bic eor orr rsb rsc sbc sub mov mvn cmn cmp teq tst b bl bx swi str strb ldr ldrb 
+  %w(adc add and bic eor orr rsb rsc sbc sub mov mvn cmn cmp teq tst b bl bx 
+    push pop swi str strb ldr ldrb 
   ).each { |inst|
     define_method(inst) { |*args|
       instruction inst.to_sym, *args
diff --git a/lib/asm/arm/instruction.rb b/lib/asm/arm/instruction.rb
index e5242a7d..5f27b239 100644
--- a/lib/asm/arm/instruction.rb
+++ b/lib/asm/arm/instruction.rb
@@ -122,7 +122,8 @@ module Asm
           end
           a.cond = COND_BITS[@cond]
           a.rn = 13 # sp
-          a.build_operand args[0]
+          puts "ARGS #{args.inspect}"
+          a.build_operand args
           a.write io, as
         when :b, :bl
           arg = args[0]
diff --git a/lib/asm/nodes.rb b/lib/asm/nodes.rb
index d34344b5..503a4a29 100644
--- a/lib/asm/nodes.rb
+++ b/lib/asm/nodes.rb
@@ -42,8 +42,13 @@ module Asm
     end
   end
 
+  #maybe not used at all as code_gen::instruction raises if used.
+  # instead now using Arrays
   class RegisterListArgNode < ArgNode
     attr_accessor :registers
+    def initialize regs
+      @registers = regs.collect{ |sym , reg| (sym == :reg) ? reg :  "not a reg #{sym} , #{reg}" }
+    end
   end
 
   class NumLiteralArgNode < ArgNode
diff --git a/test/helper.rb b/test/helper.rb
index 8da54f85..a8fe5550 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -30,3 +30,4 @@ $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'test'))
 
 require 'crystal'
 require 'asm/object_writer'
+require "asm/arm/code_generator"
diff --git a/test/test_crystal.rb b/test/test_crystal.rb
index daaf8783..54f4cb0d 100644
--- a/test/test_crystal.rb
+++ b/test/test_crystal.rb
@@ -76,6 +76,15 @@ class TestArmAsm < MiniTest::Test
     code = @generator.instance_eval { orr	r2 , r2 , r3 }.first
     assert_code code , :orr , [0x03,0x20,0x82,0xe1] #e1 82 20 03
   end
+  def test_push
+    code = @generator.instance_eval { push lr }.first
+    assert_code code , :push ,  [0x00,0x40,0x2d,0xe9] #e9 2d 40 00
+  end
+  def test_pop
+    code = @generator.instance_eval { pop	pc }.first
+    assert_code code , :pop , [0x00,0x80,0xbd,0xe8] #e8 bd 80 00
+  end
+  
   def test_rsb
     code = @generator.instance_eval { rsb	r1 , r2 , r3 }.first
     assert_code code , :rsb , [0x03,0x10,0x62,0xe0]#e0 62 10 03