diff --git a/as/k-as.py b/as/k-as.py
index b286956..df844f4 100755
--- a/as/k-as.py
+++ b/as/k-as.py
@@ -323,7 +323,6 @@ pconds = {
 }
 
 def get_cond_mask(cond, line):
-    
     mask = 0
 
     if cond[0] == 'n':
@@ -393,6 +392,13 @@ def parse_instr(line):
     # Word 2 (rep|cond|ft1|ft2)
     w2 = 0
 
+    if '.' in instr:
+        w2 |= get_cond_mask(instr.split('.', 1)[1], line)
+        instr = instr.split('.', 1)[0]
+
+    else:
+        instr = instr
+
     if instr == "rep":
         if params == None:
             print("Missing instruction after rep prefix: {}".format(line))
@@ -400,15 +406,14 @@ def parse_instr(line):
             sys.exit(1)
 
         w2 |= 0x8000    # 16th bit
-        instr, params = params.split(' ', 1)
-        
-    if '.' in instr:
-        w2 |= get_cond_mask(instr.split('.', 1)[1], line)
-        instr_name = instr.split('.', 1)[0]
 
-    else:
-        instr_name = instr
+        if len(params.split(' ', 1)) == 2:
+            instr, params = params.split(' ', 1)
+        else:
+            instr = params.split(' ', 1)[0]
+            params = None
 
+    instr_name = instr
     instr_args = ''
 
     if params == None or len(params) == 0:
diff --git a/ka/dos.k b/ka/dos.k
index 372b477..2672518 100644
--- a/ka/dos.k
+++ b/ka/dos.k
@@ -15,6 +15,12 @@ _start:
     stop
     jmp .1
 
+;
+; Essential definitions
+;
+CHAR_MAX := 0x7F
+INT_MAX := 0x7FFF
+
 ;
 ; Include librairies
 ;
diff --git a/ka/main.k b/ka/main.k
index 2e70a9f..120d35c 100644
--- a/ka/main.k
+++ b/ka/main.k
@@ -5,6 +5,26 @@
 ; Main function
 ;
 main:
+    cld
+    mov rcx, 11
+    mov rax, 33
+    mov rdi, .buf
+    mov rsi, .buf
+    rep stosb
+
+    mov rbx, rdi
+    sub rbx, rsi
+
+    mov ax0, .buf
+    mov ax1, 12
+    call print_n
+
+    ret
+
+.str1 = "Hello World!\n"
+.buf = [32]
+
+movzx_test:
     enter 1
 
     mov q[rsp], 0xFABC1234CCCCDDDD
diff --git a/vm/TODO b/vm/TODO
deleted file mode 100644
index cdb7efb..0000000
--- a/vm/TODO
+++ /dev/null
@@ -1,9 +0,0 @@
-TODO
-
-sal, sar
-imul, idiv
-
-Flags for shl, shr, mul, div
-
-Useful: https://www.felixcloutier.com/x86
-
diff --git a/vm/in/string.c b/vm/in/string.c
index 06fce6a..363105f 100644
--- a/vm/in/string.c
+++ b/vm/in/string.c
@@ -31,7 +31,7 @@ void stos_impl(ctx_t *ctx, acc_t *p1, acc_t *p2, uint len)
     
     else {
         reg = RDI;
-        val = R(rax);
+        val = rax;
     }
 
     writemem(ctx, val, R(reg), len);
@@ -45,6 +45,24 @@ IMPL_START_0(stosb)
 }
 IMPL_END;
 
+IMPL_START_0(stosw)
+{
+    stos_impl(ctx, p1, p2, 2);
+}
+IMPL_END;
+
+IMPL_START_0(stosl)
+{
+    stos_impl(ctx, p1, p2, 4);
+}
+IMPL_END;
+
+IMPL_START_0(stosq)
+{
+    stos_impl(ctx, p1, p2, 8);
+}
+IMPL_END;
+
 //----------------------------------------------------------------------------//
 
 void lods_impl(ctx_t *ctx, acc_t *p1, acc_t *p2, uint len)
@@ -75,6 +93,24 @@ IMPL_START_0(lodsb)
 }
 IMPL_END;
 
+IMPL_START_0(lodsw)
+{
+    lods_impl(ctx, p1, p2, 2);
+}
+IMPL_END;
+
+IMPL_START_0(lodsl)
+{
+    lods_impl(ctx, p1, p2, 4);
+}
+IMPL_END;
+
+IMPL_START_0(lodsq)
+{
+    lods_impl(ctx, p1, p2, 8);
+}
+IMPL_END;
+
 //----------------------------------------------------------------------------//
 
 IMPL_START_0(scasb)
diff --git a/vm/pc/decd.c b/vm/pc/decd.c
index 4bb48cb..c918693 100644
--- a/vm/pc/decd.c
+++ b/vm/pc/decd.c
@@ -345,16 +345,21 @@ do_rep:
         }
     }
 
-    if (rep && rcx > 0)
+    if (rep)
     {
         // RCX remains untouched when condition fails
         if (!eval_cond(ctx, cond))
             return;
 
+        if (rcx > 0)
+            rcx--;
+
+        if (rcx == 0)
+            return;
+
         // Show that we're REP'ing
         dump_instr(ctx, in, p1, p2, lock, rep, cond, pc);
 
-        rcx--;
         goto do_rep;
     }
 }