diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py
index e914acf71888..e4e3dca5025f 100644
--- a/lib/matplotlib/cm.py
+++ b/lib/matplotlib/cm.py
@@ -252,7 +252,7 @@ def to_rgba(self, x, alpha=None, bytes=False, norm=True):
                 else:
                     raise ValueError("third dimension must be 3 or 4")
                 if xx.dtype.kind == 'f':
-                    if norm and xx.max() > 1 or xx.min() < 0:
+                    if norm and (xx.max() > 1 or xx.min() < 0):
                         raise ValueError("Floating point image RGB values "
                                          "must be in the 0..1 range.")
                     if bytes: