diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py
index f492bb430c1..6ed13cd2f41 100644
--- a/lib/matplotlib/cm.py
+++ b/lib/matplotlib/cm.py
@@ -255,7 +255,7 @@ 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 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: