diff --git a/include/tty_ctrl.h b/include/tty_ctrl.h
index 6e2f4f3..0b77028 100644
--- a/include/tty_ctrl.h
+++ b/include/tty_ctrl.h
@@ -5,13 +5,40 @@
 #include <stddef.h>
 #include <stdio.h>
 
-bool tty_ctrl_write_fd(int fd, const char *data, size_t len);
-bool tty_ctrl_write_stream(FILE *stream, const char *data, size_t len, bool flush);
+#include "types.h"
+
+ant_value_t tty_ctrl_bool_result(ant_t *js, bool ok);
 
 const char *tty_ctrl_clear_line_seq(int dir, size_t *len_out);
 const char *tty_ctrl_clear_screen_down_seq(size_t *len_out);
 
+int tty_ctrl_normalize_clear_line_dir(int dir);
+int tty_ctrl_normalize_coord(int value);
+
+bool tty_ctrl_parse_int_value(ant_value_t value, int *out);
+bool tty_ctrl_write_fd(int fd, const char *data, size_t len);
+bool tty_ctrl_write_stream(FILE *stream, const char *data, size_t len, bool flush);
+
+bool tty_ctrl_parse_clear_line_dir(ant_value_t *args, int nargs, int dir_index, int *dir_out);
 bool tty_ctrl_build_cursor_to(char *buf, size_t buf_size, int x, bool has_y, int y, size_t *len_out);
 bool tty_ctrl_build_move_cursor_axis(char *buf, size_t buf_size, int delta, bool horizontal, size_t *len_out);
 
+typedef struct {
+  int x;
+  bool has_y;
+  int y;
+} tty_ctrl_cursor_to_args_t;
+
+bool tty_ctrl_parse_cursor_to_args(
+  ant_value_t *args, int nargs,
+  int x_index, int y_index,
+  tty_ctrl_cursor_to_args_t *out
+);
+
+bool tty_ctrl_parse_move_cursor_args(
+  ant_value_t *args, int nargs,
+  int dx_index, int dy_index,
+  int *dx, int *dy
+);
+
 #endif
diff --git a/src/modules/readline.c b/src/modules/readline.c
index add2e33..174e6f2 100644
--- a/src/modules/readline.c
+++ b/src/modules/readline.c
@@ -1193,48 +1193,40 @@ static ant_value_t rl_create_interface_promises(ant_t *js, ant_value_t *args, in
 }
 
 static ant_value_t rl_clear_line(ant_t *js, ant_value_t *args, int nargs) {
-  (void)js;
-  if (nargs < 2) return js_false;
-  int dir = (int)js_getnum(args[1]);
+  int dir = 0;
+  if (!tty_ctrl_parse_clear_line_dir(args, nargs, 1, &dir)) return js_false;
 
   size_t seq_len = 0;
   const char *seq = tty_ctrl_clear_line_seq(dir, &seq_len);
-  return js_bool(tty_ctrl_write_stream(stdout, seq, seq_len, true));
+  return tty_ctrl_bool_result(js, tty_ctrl_write_stream(stdout, seq, seq_len, true));
 }
 
 static ant_value_t rl_clear_screen_down(ant_t *js, ant_value_t *args, int nargs) {
-  (void)js; (void)args; (void)nargs;
-
   size_t seq_len = 0;
   const char *seq = tty_ctrl_clear_screen_down_seq(&seq_len);
-  return js_bool(tty_ctrl_write_stream(stdout, seq, seq_len, true));
+  return tty_ctrl_bool_result(js, tty_ctrl_write_stream(stdout, seq, seq_len, true));
 }
 
 static ant_value_t rl_cursor_to(ant_t *js, ant_value_t *args, int nargs) {
-  (void)js;
-  if (nargs < 2) return js_false;
-  int x = (int)js_getnum(args[1]);
+  tty_ctrl_cursor_to_args_t parsed;
+  if (!tty_ctrl_parse_cursor_to_args(args, nargs, 1, 2, &parsed)) return js_false;
 
   char seq[64];
   size_t seq_len = 0;
-  bool ok = false;
-  if (nargs >= 3 && vtype(args[2]) == T_NUM) {
-    int y = (int)js_getnum(args[2]);
-    ok = tty_ctrl_build_cursor_to(seq, sizeof(seq), x, true, y, &seq_len);
-  } else {
-    ok = tty_ctrl_build_cursor_to(seq, sizeof(seq), x, false, 0, &seq_len);
-  }
+  bool ok = tty_ctrl_build_cursor_to(
+    seq, sizeof(seq),
+    parsed.x, parsed.has_y, parsed.y,
+    &seq_len
+  );
   if (!ok) return js_false;
 
-  return js_bool(tty_ctrl_write_stream(stdout, seq, seq_len, true));
+  return tty_ctrl_bool_result(js, tty_ctrl_write_stream(stdout, seq, seq_len, true));
 }
 
 static ant_value_t rl_move_cursor(ant_t *js, ant_value_t *args, int nargs) {
-  (void)js;
-  if (nargs < 3) return js_false;
-
-  int dx = (int)js_getnum(args[1]);
-  int dy = (int)js_getnum(args[2]);
+  int dx = 0;
+  int dy = 0;
+  if (!tty_ctrl_parse_move_cursor_args(args, nargs, 1, 2, &dx, &dy)) return js_false;
 
   bool ok = true;
   if (dx != 0) {
@@ -1252,7 +1244,7 @@ static ant_value_t rl_move_cursor(ant_t *js, ant_value_t *args, int nargs) {
   }
 
   if (!ok) return js_false;
-  return js_bool(fflush(stdout) == 0);
+  return tty_ctrl_bool_result(js, fflush(stdout) == 0);
 }
 
 static ant_value_t rl_emit_keypress_events(ant_t *js, ant_value_t *args, int nargs) {
diff --git a/src/modules/tty.c b/src/modules/tty.c
index 4b9243a..9050e2c 100644
--- a/src/modules/tty.c
+++ b/src/modules/tty.c
@@ -1,6 +1,5 @@
 #include <compat.h> // IWYU pragma: keep
 
-#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -43,20 +42,9 @@ static inline bool is_callable(ant_value_t value) {
   return t == T_FUNC || t == T_CFUNC;
 }
 
-static bool parse_int(ant_value_t value, int *out) {
-  if (vtype(value) != T_NUM) return false;
-  double d = js_getnum(value);
-  if (!isfinite(d)) return false;
-  if (d < (double)INT_MIN || d > (double)INT_MAX) return false;
-  int i = (int)d;
-  if ((double)i != d) return false;
-  *out = i;
-  return true;
-}
-
 static bool parse_fd(ant_value_t value, int *fd_out) {
   int fd = 0;
-  if (!parse_int(value, &fd)) return false;
+  if (!tty_ctrl_parse_int_value(value, &fd)) return false;
   if (fd < 0) return false;
   *fd_out = fd;
   return true;
@@ -413,7 +401,7 @@ static ant_value_t tty_write_stream_clear_line(ant_t *js, ant_value_t *args, int
   ant_value_t this_obj = js_getthis(js);
 
   int dir = 0;
-  if (nargs > 0 && vtype(args[0]) != T_UNDEF && !parse_int(args[0], &dir)) {
+  if (!tty_ctrl_parse_clear_line_dir(args, nargs, 0, &dir)) {
     return js_mkerr_typed(js, JS_ERR_TYPE, "clearLine(dir) requires a numeric dir");
   }
 
@@ -442,13 +430,12 @@ static ant_value_t tty_write_stream_clear_screen_down(ant_t *js, ant_value_t *ar
 
 static ant_value_t tty_write_stream_cursor_to(ant_t *js, ant_value_t *args, int nargs) {
   ant_value_t this_obj = js_getthis(js);
-  if (nargs < 1 || !parse_int(args[0], &(int){0})) {
+  int x = 0;
+  if (nargs < 1 || !tty_ctrl_parse_int_value(args[0], &x)) {
     return js_mkerr_typed(js, JS_ERR_TYPE, "cursorTo(x[, y][, callback]) requires numeric x");
   }
 
-  int x = 0;
-  (void)parse_int(args[0], &x);
-  if (x < 0) x = 0;
+  x = tty_ctrl_normalize_coord(x);
 
   bool has_y = false;
   int y = 0;
@@ -459,9 +446,9 @@ static ant_value_t tty_write_stream_cursor_to(ant_t *js, ant_value_t *args, int
       cb = args[1];
     } else if (vtype(args[1]) == T_UNDEF) {
       // no-op
-    } else if (parse_int(args[1], &y)) {
+    } else if (tty_ctrl_parse_int_value(args[1], &y)) {
       has_y = true;
-      if (y < 0) y = 0;
+      y = tty_ctrl_normalize_coord(y);
       if (nargs > 2 && is_callable(args[2])) cb = args[2];
     } else {
       return js_mkerr_typed(js, JS_ERR_TYPE, "cursorTo y must be a number when provided");
@@ -487,7 +474,7 @@ static ant_value_t tty_write_stream_move_cursor(ant_t *js, ant_value_t *args, in
 
   int dx = 0;
   int dy = 0;
-  if (!parse_int(args[0], &dx) || !parse_int(args[1], &dy)) {
+  if (!tty_ctrl_parse_move_cursor_args(args, nargs, 0, 1, &dx, &dy)) {
     return js_mkerr_typed(js, JS_ERR_TYPE, "moveCursor(dx, dy[, callback]) requires numeric dx and dy");
   }
 
@@ -534,7 +521,7 @@ static ant_value_t tty_write_stream_has_colors(ant_t *js, ant_value_t *args, int
   if (nargs > 0) {
     if (vtype(args[0]) == T_NUM) {
       int parsed_count = 16;
-      if (!parse_int(args[0], &parsed_count)) {
+      if (!tty_ctrl_parse_int_value(args[0], &parsed_count)) {
         return js_mkerr_typed(js, JS_ERR_TYPE, "hasColors(count[, env]) count must be an integer");
       }
       count = parsed_count;
diff --git a/src/tty_ctrl.c b/src/tty_ctrl.c
index f213c04..f47bdcc 100644
--- a/src/tty_ctrl.c
+++ b/src/tty_ctrl.c
@@ -1,7 +1,8 @@
 #include <compat.h> // IWYU pragma: keep
-#include "tty_ctrl.h"
 
 #include <errno.h>
+#include <limits.h>
+#include <math.h>
 #include <stdio.h>
 #include <string.h>
 
@@ -13,6 +14,9 @@
 #define ANT_WRITE_FD write
 #endif
 
+#include "tty_ctrl.h"
+#include "internal.h"
+
 bool tty_ctrl_write_fd(int fd, const char *data, size_t len) {
   if (fd < 0 || !data) return false;
   if (len == 0) return true;
@@ -46,7 +50,78 @@ bool tty_ctrl_write_stream(FILE *stream, const char *data, size_t len, bool flus
   return true;
 }
 
+bool tty_ctrl_parse_int_value(ant_value_t value, int *out) {
+  if (vtype(value) != T_NUM) return false;
+  double d = js_getnum(value);
+  if (!isfinite(d)) return false;
+  if (d < (double)INT_MIN || d > (double)INT_MAX) return false;
+  int i = (int)d;
+  if ((double)i != d) return false;
+  *out = i;
+  return true;
+}
+
+int tty_ctrl_normalize_clear_line_dir(int dir) {
+  if (dir < 0) return -1;
+  if (dir > 0) return 1;
+  return 0;
+}
+
+int tty_ctrl_normalize_coord(int value) {
+  return value < 0 ? 0 : value;
+}
+
+bool tty_ctrl_parse_clear_line_dir(ant_value_t *args, int nargs, int dir_index, int *dir_out) {
+  int dir = 0;
+  if (nargs > dir_index && vtype(args[dir_index]) != T_UNDEF) {
+    if (!tty_ctrl_parse_int_value(args[dir_index], &dir)) return false;
+  }
+  *dir_out = tty_ctrl_normalize_clear_line_dir(dir);
+  return true;
+}
+
+bool tty_ctrl_parse_cursor_to_args(
+  ant_value_t *args,
+  int nargs,
+  int x_index,
+  int y_index,
+  tty_ctrl_cursor_to_args_t *out
+) {
+  if (!out || nargs <= x_index) return false;
+
+  int x = 0;
+  if (!tty_ctrl_parse_int_value(args[x_index], &x)) return false;
+  out->x = tty_ctrl_normalize_coord(x);
+  out->has_y = false;
+  out->y = 0;
+
+  if (nargs > y_index && vtype(args[y_index]) != T_UNDEF) {
+    int y = 0;
+    if (!tty_ctrl_parse_int_value(args[y_index], &y)) return false;
+    out->has_y = true;
+    out->y = tty_ctrl_normalize_coord(y);
+  }
+
+  return true;
+}
+
+bool tty_ctrl_parse_move_cursor_args(
+  ant_value_t *args,
+  int nargs,
+  int dx_index,
+  int dy_index,
+  int *dx,
+  int *dy
+) {
+  if (!dx || !dy) return false;
+  if (nargs <= dy_index) return false;
+  if (!tty_ctrl_parse_int_value(args[dx_index], dx)) return false;
+  if (!tty_ctrl_parse_int_value(args[dy_index], dy)) return false;
+  return true;
+}
+
 const char *tty_ctrl_clear_line_seq(int dir, size_t *len_out) {
+  dir = tty_ctrl_normalize_clear_line_dir(dir);
   const char *seq = "\033[2K\r";
   if (dir < 0) seq = "\033[1K";
   else if (dir > 0) seq = "\033[0K";
@@ -92,3 +167,7 @@ bool tty_ctrl_build_move_cursor_axis(char *buf, size_t buf_size, int delta, bool
   if (len_out) *len_out = (size_t)n;
   return true;
 }
+
+ant_value_t tty_ctrl_bool_result(ant_t *js, bool ok) {
+  return js_bool(ok);
+}