diff --git a/asm/creole.py b/asm/creole.py
index e48d65f..2e323e4 100644
--- a/asm/creole.py
+++ b/asm/creole.py
@@ -165,18 +165,18 @@ class Line:
 		self.opcode = opcode
 		self.args = args
 
-	def check_line(self, labnum, regnum):
+	def check_line(self, lablen, reglen):
 		for a in self.args:
 			if a[0] == ArgType.REG:
-				if a[1] < 0 or a[1] >= regnum:
+				if a[1] < 0 or a[1] >= reglen:
 					raise RangeCheckException(a[0],
 					                          a[1],
-					                          regnum)
+					                          reglen)
 			elif a[0] == ArgType.LAB:
-				if a[1] < 0 or a[1] >= labnum:
+				if a[1] < 0 or a[1] >= lablen:
 					raise RangeCheckException(a[0],
 					                          a[1],
-					                          regnum)
+					                          reglen)
 
 	def __call__(self):
 		b = bytes([self.opcode])
@@ -193,7 +193,7 @@ class InstructionNotFoundException(Exception):
 class Program:
 	def asm_push_line(self, ins, args):
 		l = Line(ins, args)
-		l.check_line(self.labnum, self.regnum)
+		l.check_line(self.lablen, self.reglen)
 		self.asm.append(l)
 
 	def parse_asm_line(self, line):
@@ -214,8 +214,8 @@ class Program:
 			b = b + line()
 		return b
 
-	def __init__(self, labnum=16, regnum=16):
+	def __init__(self, lablen=16, reglen=16):
 		self.asm = []
-		self.labnum = labnum
-		self.regnum = regnum
+		self.lablen = lablen
+		self.reglen = reglen
 
diff --git a/asm/test.py b/asm/test.py
index 73568cc..bddf0a3 100644
--- a/asm/test.py
+++ b/asm/test.py
@@ -47,7 +47,7 @@ class PushTest(unittest.TestCase):
 		self.assertEqual(cm.exception.argtypelen, 1)
 
 	def test_large_reg(self):
-		p = Program(regnum=0x8000000)
+		p = Program(reglen=0x8000000)
 		p.parse_asm_line("PUSH r134217727")
 		b = p()
 		self.assertEqual(b, b'\x01\xFC\x87\xbf\xbf\xbf\xbf\x00')
@@ -78,6 +78,26 @@ class PushTest(unittest.TestCase):
 		self.assertEqual(ex.cenv.prg[1].w[1], 0)
 		self.assertEqual(ex.cenv.prg[1].w[2], 0)
 
+	def test_push_many(self):
+		p = Program()
+		stklen = 40
+		for n in range(0,stklen):
+			p.parse_asm_line("PUSH 5")
+		ex = ffi.Environment(stklen=stklen)
+		self.assertEqual(ex.load(p()), ffi.CompileRet.OK)
+		self.assertEqual(ex(), ffi.RunRet.STOP)
+		for n in range(0,stklen):
+			self.assertEqual(ex.cenv.stk[n], 5)
+
+	def test_push_overflow(self):
+		p = Program()
+		stklen = 40
+		for n in range(0, stklen + 1):
+			p.parse_asm_line("PUSH 5")
+		ex = ffi.Environment(stklen=stklen)
+		self.assertEqual(ex.load(p()), ffi.CompileRet.OK)
+		self.assertEqual(ex(), ffi.RunRet.STACK_OVERFLOW)
+
 class PopTest(unittest.TestCase):
 	def test_compile_pop_reg(self):
 		p = Program()
@@ -117,18 +137,33 @@ class PopTest(unittest.TestCase):
 	def test_compile_throw_argument_overflow(self):
 		p = Program()
 		with self.assertRaises(TypecheckLenException) as cm:
-			p.parse_asm_line("push r1 r2")
-		self.assertEqual(cm.exception.opcode, 1)
+			p.parse_asm_line("pop r1 r2")
+		self.assertEqual(cm.exception.opcode, 2)
 		self.assertEqual(cm.exception.insargs, ["r1", "r2"])
 		self.assertEqual(cm.exception.argtypelen, 1)
 
 	def test_catch_typecheck_argument_underflow(self):
 		p = Program()
 		with self.assertRaises(TypecheckLenException) as cm:
-			p.parse_asm_line("push")
-		self.assertEqual(cm.exception.opcode, 1)
+			p.parse_asm_line("pop")
+		self.assertEqual(cm.exception.opcode, 2)
 		self.assertEqual(cm.exception.insargs, [])
-		self.assertEqual(cm.exception.argtypelen, 1)
+
+	def test_pop_underflow(self):
+		p = Program()
+		p.parse_asm_line("pop r0")
+		ex = ffi.Environment()
+		self.assertEqual(ex.load(p()), ffi.CompileRet.OK)
+		self.assertEqual(ex(), ffi.RunRet.STACK_UNDERFLOW)
+
+	def test_pop_underflow_2(self):
+		p = Program()
+		p.parse_asm_line("push 5")
+		p.parse_asm_line("pop r0")
+		p.parse_asm_line("pop r1")
+		ex = ffi.Environment()
+		self.assertEqual(ex.load(p()), ffi.CompileRet.OK)
+		self.assertEqual(ex(), ffi.RunRet.STACK_UNDERFLOW)
 
 class AddTest(unittest.TestCase):
 	def test_exec_add(self):
@@ -150,7 +185,6 @@ class AddTest(unittest.TestCase):
 		self.assertEqual(ex.cenv.reg[0], 30)
 		self.assertEqual(ex.cenv.reg[1], word_2c(10))
 
-class AddTest(unittest.TestCase):
 	def test_exec_mul_throw_imm(self):
 		p = Program()
 		with self.assertRaises(TypecheckException) as cm:
@@ -187,6 +221,7 @@ class AddTest(unittest.TestCase):
 		self.assertEqual(cm.exception.i, 2)
 		self.assertEqual(cm.exception.opcode, 3)
 
+class MulTest(unittest.TestCase):
 	def test_exec_mul_imm_imm(self):
 		p = Program()
 		p.parse_asm_line("mul r0 2 2")