diff --git a/byterun/Sort.bc b/byterun/Sort.bc
deleted file mode 100644
index 29990be1a..000000000
Binary files a/byterun/Sort.bc and /dev/null differ
diff --git a/byterun/include/stack.h b/byterun/include/stack.h
index df60e8a61..e6b9f0c6f 100644
--- a/byterun/include/stack.h
+++ b/byterun/include/stack.h
@@ -66,8 +66,12 @@ static inline void s_push_i(aint val) { s_push((void *)val); }
 static inline void s_push_nil() { s_push(NULL); }
 
 static inline void s_pushn_nil(size_t n) {
+  if ((void **)__gc_stack_top + (aint)n - 1 <= s.stack) {
+    s_failure(&s, "stack overflow");
+  }
   for (size_t i = 0; i < n; ++i) {
-    s_push(NULL);
+    __gc_stack_top -= sizeof(void *);
+    *(void **)__gc_stack_top = NULL;
   }
 }
 
@@ -82,7 +86,6 @@ static inline void *s_pop() {
   printf("--> pop\n");
 #endif
   void *value = *(void **)__gc_stack_top;
-  // *(void **)__gc_stack_top = NULL;
   __gc_stack_top += sizeof(void *);
   return value;
 }
@@ -90,9 +93,10 @@ static inline void *s_pop() {
 static inline aint s_pop_i() { return (aint)s_pop(); }
 
 static inline void s_popn(size_t n) {
-  for (size_t i = 0; i < n; ++i) {
-    s_pop();
+  if ((void **)__gc_stack_top + (aint)n - 1 >= s_top()) {
+    s_failure(&s, "empty stack");
   }
+  __gc_stack_top += n * sizeof(void *);
 }
 
 // ------ functions ------
diff --git a/byterun/src/cli.c b/byterun/src/cli.c
index c0d0a2dc3..b580ffb2c 100644
--- a/byterun/src/cli.c
+++ b/byterun/src/cli.c
@@ -8,7 +8,6 @@ int main(int argc, char** argv) {
     failure("no file name provided");
   }
 
-  // printf("size of aint is %i\n", sizeof(aint));
   bytefile *f = read_file(argv[1]);
 // #ifdef DEBUG_VERSION
 //   dump_file (stdout, f);
diff --git a/byterun/src/interpreter.c b/byterun/src/interpreter.c
index b215a50c1..9ed9df2b5 100644
--- a/byterun/src/interpreter.c
+++ b/byterun/src/interpreter.c
@@ -40,27 +40,6 @@ void run(bytefile *bf, int argc, char **argv) {
   printf("--- interpreter run ---\n");
 #endif
 
-  // const char *ops[] = {
-  //     "+", "-", "*", "/", "%", "<", "<=", ">", ">=", "==", "!=", "&&", "!!"};
-  // aint (*ops_func[])(void *, void *) = {
-  //     &Ls__Infix_43,   // +
-  //     &Ls__Infix_45,   // -
-  //     &Ls__Infix_42,   // *
-  //     &Ls__Infix_47,   // /
-  //     &Ls__Infix_37,   // %
-  //     &Ls__Infix_60,   // <
-  //     &Ls__Infix_6061, // <=
-  //     &Ls__Infix_62,   // >
-  //     &Ls__Infix_6261, // >=
-  //     &Ls__Infix_6161, // ==
-  //     &Ls__Infix_3361, // !=
-  //     &Ls__Infix_3838, // &&
-  //     &Ls__Infix_3333, // !!
-  // };
-
-  // const char *pats[] = {"=str", "#string", "#array", "#sexp",
-  //                       "#ref", "#val",    "#fun"};
-
   // argc, argv
   {
     s_push_i(BOX(argc));
@@ -78,7 +57,6 @@ void run(bytefile *bf, int argc, char **argv) {
 #endif
 
   do {
-    // char *before_op_ip = s.ip; // save to set s.prev_ip
     bool call_happened = false;
 
     if (s.ip >= bf->code_ptr + bf->code_size) {
@@ -104,7 +82,7 @@ void run(bytefile *bf, int argc, char **argv) {
     case CMD_BINOP: { // BINOP ops[l-1]
       void *left = s_pop();
       void *right = s_pop();
-      switch ((int)l) {
+      switch (l) {
       case CMD_BINOP_ADD: // +
         s_push_i(Ls__Infix_43(right, left));
         break;