diff --git a/win2xcur/main/win2xcur.py b/win2xcur/main/win2xcur.py
index ad570e0..5c5505d 100644
--- a/win2xcur/main/win2xcur.py
+++ b/win2xcur/main/win2xcur.py
@@ -32,10 +32,10 @@ def main() -> None:
                         help='y-offset of shadow (as fraction of height)')
     parser.add_argument('-c', '--shadow-color', default='#000000',
                         help='color of the shadow')
-    parser.add_argument('--scale', default=None, type=str,
+    parser.add_argument('--scale', nargs='*', type=float, default=None,
                         help='Scale the cursor by the specified factor. Multi-scale "[0.125,0.1875,0.25]"')
-    parser.add_argument('--size', default=None, type=str,
-                        help='Scale the cursor to the specified size. Multi-size "[32,28,64]"')
+    parser.add_argument('--size', nargs='*', type=int, default=None,
+                        help='Scale the cursor to the specified size. Multi-size "[32,48,64]"')
 
     args = parser.parse_args()
     print_lock = Lock()
@@ -51,17 +51,11 @@ def main() -> None:
                 traceback.print_exc()
         else:
             if args.scale:
-                scales = eval(args.scale)
-                if isinstance(scales, (int, float)):
-                    scale.apply_to_frames(cursor.frames, scale=scales)
-                else:
-                    cursor.frames = scale.apply_to_frames_MS(cursor.frames, scales=scales)
+                cursor.frames = scale.apply_to_frames_by_scales(cursor.frames, scales=args.scale)
             elif args.size:
-                sizes = eval(args.size)
-                if isinstance(sizes, (int, float)):
-                    scale.apply_to_frames(cursor.frames, size=sizes)
-                else:
-                    cursor.frames = scale.apply_to_frames_MS(cursor.frames, sizes=sizes)
+                cursor.frames = scale.apply_to_frames_to_sizes(cursor.frames, sizes=args.size)
+            else:
+                raise NotImplementedError('Please specify either --scale or --size')
 
             if args.shadow:
                 shadow.apply_to_frames(cursor.frames, color=args.shadow_color, radius=args.shadow_radius,
diff --git a/win2xcur/main/x2wincur.py b/win2xcur/main/x2wincur.py
index 298a9d6..7bdeacd 100644
--- a/win2xcur/main/x2wincur.py
+++ b/win2xcur/main/x2wincur.py
@@ -18,9 +18,9 @@ def main() -> None:
                         help='X11 cursor files to convert (no extension)')
     parser.add_argument('-o', '--output', '--output-dir', default=os.curdir,
                         help='Directory to store converted cursor files.')
-    parser.add_argument('-S', '--scale', default=None, type=str,
+    parser.add_argument('-S', '--scale', nargs='*', type=float, default=None,
                         help='Scale the cursor by the specified factor. Multi-scale "[0.125,0.1875,0.25]"')
-    parser.add_argument('--size', default=None, type=str,
+    parser.add_argument('--size', nargs='*', type=int, default=None,
                         help='Scale the cursor to the specified size. Multi-size "[32,28,64]"')
 
     args = parser.parse_args()
@@ -37,17 +37,11 @@ def main() -> None:
                 traceback.print_exc()
         else:
             if args.scale:
-                scales = eval(args.scale)
-                if isinstance(scales, (int, float)):
-                    scale.apply_to_frames(cursor.frames, scale=scales)
-                else:
-                    cursor.frames = scale.apply_to_frames_MS(cursor.frames, scales=scales)
+                cursor.frames = scale.apply_to_frames_by_scales(cursor.frames, scales=args.scale)
             elif args.size:
-                sizes = eval(args.size)
-                if isinstance(sizes, (int, float)):
-                    scale.apply_to_frames(cursor.frames, size=sizes)
-                else:
-                    cursor.frames = scale.apply_to_frames_MS(cursor.frames, sizes=sizes)
+                cursor.frames = scale.apply_to_frames_to_sizes(cursor.frames, sizes=args.size)
+            else:
+                raise NotImplementedError('Please specify either --scale or --size')
 
             ext, result = to_smart(cursor.frames)
             output = os.path.join(args.output, os.path.basename(name) + ext)
diff --git a/win2xcur/scale.py b/win2xcur/scale.py
index 337bd04..e9c111e 100644
--- a/win2xcur/scale.py
+++ b/win2xcur/scale.py
@@ -2,32 +2,35 @@ from typing import List
 
 from win2xcur.cursor import CursorFrame
 
+def apply_to_frames_by_scales(frames: List[CursorFrame], *, scales: List[float] = None) -> List[CursorFrame]:
+    all_frames = []
+    for scale in scales:
+        for frame in frames:
+            frame = frame.clone()
+            for cursor in frame:
+                cursor.image.scale(
+                    int(round(cursor.image.width * scale)),
+                    int(round(cursor.image.height * scale)),
+                )
+                cursor.nominal = int(cursor.nominal * scale)
+                hx, hy = cursor.hotspot
+                cursor.hotspot = (int(hx * scale), int(hy * scale))
+            all_frames.append(frame)
+    return all_frames
 
-def apply_to_frames(frames: List[CursorFrame], *, scale: float = None, size: int = None) -> None:
-    for frame in frames:
-        for cursor in frame:
-            if size:
+def apply_to_frames_to_sizes(frames: List[CursorFrame], *, sizes: List[int] = None) -> List[CursorFrame]:
+    all_frames = []
+    for size in sizes:
+        for frame in frames:
+            frame = frame.clone()
+            for cursor in frame:
                 scale = size / cursor.image.width
-            cursor.image.scale(
-                size or int(round(cursor.image.width * scale)),
-                size or int(round(cursor.image.height * scale)),
-            )
-            cursor.nominal = int(cursor.nominal * scale)
-            hx, hy = cursor.hotspot
-            cursor.hotspot = (int(hx * scale), int(hy * scale))
-
-
-def apply_to_frames_MS(frames: List[CursorFrame], *, scales: List[float] = None,
-                       sizes: List[int] = None) -> List[CursorFrame]:
-    frames_MS = []
-    if scales is not None:
-        for scale in scales:
-            frames_s = [frame.clone() for frame in frames]
-            apply_to_frames(frames_s, scale=scale)
-            frames_MS.extend(frames_s)
-    else:
-        for size in sizes:
-            frames_s = [frame.clone() for frame in frames]
-            apply_to_frames(frames_s, size=size)
-            frames_MS.extend(frames_s)
-    return frames_MS
+                cursor.image.scale(
+                    size,
+                    size,
+                )
+                cursor.nominal = int(cursor.nominal * scale)
+                hx, hy = cursor.hotspot
+                cursor.hotspot = (int(hx * scale), int(hy * scale))
+            all_frames.append(frame)
+    return all_frames