diff --git a/src/PIL/ImageMath.py b/src/PIL/ImageMath.py
index 2c73acb9792..04718719522 100644
--- a/src/PIL/ImageMath.py
+++ b/src/PIL/ImageMath.py
@@ -20,10 +20,6 @@
 from . import Image, _imagingmath
 
 
-def _isconstant(v):
-    return isinstance(v, (int, float))
-
-
 class _Operand:
     """Wraps an image operand, providing standard operators"""
 
@@ -43,7 +39,7 @@ def __fixup(self, im1):
                 raise ValueError(msg)
         else:
             # argument was a constant
-            if _isconstant(im1) and self.im.mode in ("1", "L", "I"):
+            if isinstance(im1, (int, float)) and self.im.mode in ("1", "L", "I"):
                 return Image.new("I", self.im.size, im1)
             else:
                 return Image.new("F", self.im.size, im1)