diff --git a/wxPython/src/_sizers.i b/wxPython/src/_sizers.i
index b2b81d6cf8..ab10c04355 100644
--- a/wxPython/src/_sizers.i
+++ b/wxPython/src/_sizers.i
@@ -733,7 +733,7 @@ the item to be found.", "");
                 return self._ReplaceWin(olditem, item, recursive)
             elif isinstance(olditem, wx.Sizer):
                 return self._ReplaceSizer(olditem, item, recursive)
-            elif isinstnace(olditem, int):
+            elif isinstance(olditem, int):
                 return self._ReplaceItem(olditem, item)
             else:
                 raise TypeError("Expected Window, Sizer, or integer for first parameter.")
diff --git a/wxPython/src/gtk/_core.py b/wxPython/src/gtk/_core.py
index 1f1ff4d09d..ed48f60738 100644
--- a/wxPython/src/gtk/_core.py
+++ b/wxPython/src/gtk/_core.py
@@ -12054,7 +12054,7 @@ class Sizer(Object):
             return self._ReplaceWin(olditem, item, recursive)
         elif isinstance(olditem, wx.Sizer):
             return self._ReplaceSizer(olditem, item, recursive)
-        elif isinstnace(olditem, int):
+        elif isinstance(olditem, int):
             return self._ReplaceItem(olditem, item)
         else:
             raise TypeError("Expected Window, Sizer, or integer for first parameter.")
diff --git a/wxPython/src/mac/_core.py b/wxPython/src/mac/_core.py
index 1f1ff4d09d..ed48f60738 100644
--- a/wxPython/src/mac/_core.py
+++ b/wxPython/src/mac/_core.py
@@ -12054,7 +12054,7 @@ class Sizer(Object):
             return self._ReplaceWin(olditem, item, recursive)
         elif isinstance(olditem, wx.Sizer):
             return self._ReplaceSizer(olditem, item, recursive)
-        elif isinstnace(olditem, int):
+        elif isinstance(olditem, int):
             return self._ReplaceItem(olditem, item)
         else:
             raise TypeError("Expected Window, Sizer, or integer for first parameter.")
diff --git a/wxPython/src/msw/_core.py b/wxPython/src/msw/_core.py
index 506b653f0e..1457f8c2cf 100644
--- a/wxPython/src/msw/_core.py
+++ b/wxPython/src/msw/_core.py
@@ -12058,7 +12058,7 @@ class Sizer(Object):
             return self._ReplaceWin(olditem, item, recursive)
         elif isinstance(olditem, wx.Sizer):
             return self._ReplaceSizer(olditem, item, recursive)
-        elif isinstnace(olditem, int):
+        elif isinstance(olditem, int):
             return self._ReplaceItem(olditem, item)
         else:
             raise TypeError("Expected Window, Sizer, or integer for first parameter.")