diff --git a/_fakeduck.vp b/_fakeduck.vp
index 8b90aed..74414f5 100644
--- a/_fakeduck.vp
+++ b/_fakeduck.vp
@@ -22,7 +22,7 @@ class _str:
         for i, ch in enumerate(src):
             if ch >= 97:
                 if ch <= 122:
-                    buf[i] = ch - 32
+                    buf[i] = char(ch - 32)
                 else:
                     buf[i] = ch
             else:
@@ -38,7 +38,7 @@ class _str:
         for i, ch in enumerate(src):
             if ch >= 65:
                 if ch <= 90:
-                    buf[i] = ch + 32
+                    buf[i] = char(ch + 32)
                 else:
                     buf[i] = ch
             else:
@@ -57,7 +57,7 @@ class _str:
                 first = False
                 if ch >= 97:
                     if ch <= 122:
-                        buf[i] = ch - 32
+                        buf[i] = char(ch - 32)
                     else:
                         buf[i] = ch
                 else:
@@ -65,7 +65,7 @@ class _str:
             else:
                 if ch >= 65:
                     if ch <= 90:
-                        buf[i] = ch + 32
+                        buf[i] = char(ch + 32)
                     else:
                         buf[i] = ch
                 else:
@@ -81,13 +81,13 @@ class _str:
         for i, ch in enumerate(src):
             if ch >= 97:
                 if ch <= 122:
-                    buf[i] = ch - 32
+                    buf[i] = char(ch - 32)
                 else:
                     buf[i] = ch
             else:
                 if ch >= 65:
                     if ch <= 90:
-                        buf[i] = ch + 32
+                        buf[i] = char(ch + 32)
                     else:
                         buf[i] = ch
                 else:
@@ -114,7 +114,7 @@ class _str:
                 if prev_alpha:
                     if ch >= 65:
                         if ch <= 90:
-                            buf[i] = ch + 32
+                            buf[i] = char(ch + 32)
                         else:
                             buf[i] = ch
                     else:
@@ -122,7 +122,7 @@ class _str:
                 else:
                     if ch >= 97:
                         if ch <= 122:
-                            buf[i] = ch - 32
+                            buf[i] = char(ch - 32)
                         else:
                             buf[i] = ch
                     else:
@@ -141,7 +141,7 @@ class _str:
         for i, ch in enumerate(src):
             if ch >= 65:
                 if ch <= 90:
-                    buf[i] = ch + 32
+                    buf[i] = char(ch + 32)
                 else:
                     buf[i] = ch
             else:
diff --git a/sys.vp b/sys.vp
index 4569988..87f420c 100644
--- a/sys.vp
+++ b/sys.vp
@@ -105,7 +105,7 @@ def _init_argv_win32():
                 argv_arr[argc] = str(buf + j)
                 argc += 1
                 in_arg = True
-            buf[j] = ch
+            buf[j] = char(ch)
             j += 1
     if in_arg: buf[j] = 0
     _argc = argc