diff --git a/abr_control/interfaces/pygame.py b/abr_control/interfaces/pygame.py
index 13b884a6..00d8032e 100644
--- a/abr_control/interfaces/pygame.py
+++ b/abr_control/interfaces/pygame.py
@@ -83,7 +83,7 @@ def __init__(
         # create transparent arm lines
         self.lines_base = []
         for ii, L in enumerate(self.L):
-            self.lines_base.append(pygame.Surface((L, line_width), pygame.SRCALPHA, 32))
+            self.lines_base.append(pygame.Surface((int(L), line_width), pygame.SRCALPHA, 32))
             # color in transparent arm lines
             self.lines_base[ii].fill(line_color)