diff --git a/Makefile b/Makefile
index 1263ec0..eaf5f6f 100644
--- a/Makefile
+++ b/Makefile
@@ -2,19 +2,19 @@
 # See the LICENSE file in the project root for more information.
 
 all: kas
-# kas
 
 kpc:
 	@cd pc && make --no-print-directory
 
-kas: kpc as/k-as.py as/regs.lst as/testfile.k
+kas: kpc as/k-as.py as/regs.lst
 	@cp pc/instrs/instrs.lst as
 	@rm -f pc/instrs/instrs.lst
 
-test: kas
-	@cd as && ./k-as.py testfile.k 0x100000 testfile.out
-	@pc/k.exe as/testfile.out
+asm: os/dos.k
+	@cd os && ../as/k-as.py dos.k 0x100000 a.out
 
-disasm: kas
-	@cd as && ./k-as.py testfile.k 0x100000 testfile.out
-	@pc/k.exe as/testfile.out -d
+test: kas asm
+	@pc/k.exe os/a.out
+
+disasm: kas asm
+	@pc/k.exe os/a.out -d
diff --git a/as/k-as.py b/as/k-as.py
index d100eef..5101c6e 100755
--- a/as/k-as.py
+++ b/as/k-as.py
@@ -3,6 +3,7 @@
 # The OS/K Team licenses this file to you under the MIT license.
 # See the LICENSE file in the project root for more information.
 
+import os
 import sys
 import subprocess
 from array import array
@@ -17,8 +18,8 @@ instrs = open(".{}.instr".format(sys.argv[3]), "w+")
 b_data = open(".{}.data".format(sys.argv[3]), "w+b")
 b_text = open(".{}.text".format(sys.argv[3]), "w+b")
 
-lst_regs = open("regs.lst")
-lst_instrs = open("instrs.lst")
+lst_regs = open(os.path.join(sys.path[0], "regs.lst"))
+lst_instrs = open(os.path.join(sys.path[0], "instrs.lst"))
 
 fi = open(sys.argv[1])
 b_out = open(sys.argv[3], "wb")
@@ -199,7 +200,7 @@ def parse():
         if line[0] == ' ' or line[0] == '\t':
             line = line.lstrip()
 
-            if line[0] == '#' or line[0] == ';':
+            if line[0] in '#;@!/':
                 continue
 
             ok, line = apply_pdefs(line)
diff --git a/as/testfile.k b/os/dos.k
similarity index 92%
rename from as/testfile.k
rename to os/dos.k
index 97edf36..13a30ad 100644
--- a/as/testfile.k
+++ b/os/dos.k
@@ -3,6 +3,8 @@
 
 hw = "Hello World"
 
+;
+; void main(void)
 ;
 ; Entry point
 ;
@@ -13,11 +15,6 @@ main:
 
     mov ax0, hw
     call print
-
-;    mov ax0, hw
-;    mov ax1, hw_len
-;    call print_n
-
     stop
 
 ;
@@ -45,7 +42,6 @@ print:
     leave
     ret
 
-
 ;
 ; void print_n(char *, int)
 ;
diff --git a/pc/regs.c b/pc/regs.c
index 469df6e..446a314 100644
--- a/pc/regs.c
+++ b/pc/regs.c
@@ -5,7 +5,7 @@
 
 reg_t arch_r[NREGS] =
 {
-    { "inv", "Invalid register", 0, RES },
+    { "inv", "Invalid register", "Invalid", 0, RES },
 
     { "rip", "Instruction pointer", "Special; Volatile", 0, RES },
     { "flg", "Flags register", "Special; Volatile", 0, RES },
@@ -71,7 +71,7 @@ void dumpregs(ctx_t *ctx)
     int i;
     reg_t *r;
     
-    //assert(ctx->r[INV].val == 0);
+    assert(ctx->r[INV].val == 0);
     
     log("\nRegisters:\n");
     log("rip=0x%-16lX flg=0x%-16lX ", ctx->r[RIP].val, ctx->r[FLG].val);