diff --git a/PyMca5/PyMcaGraph/backends/MatplotlibBackend.py b/PyMca5/PyMcaGraph/backends/MatplotlibBackend.py
index c3ced2f9d..f4d4ae37c 100644
--- a/PyMca5/PyMcaGraph/backends/MatplotlibBackend.py
+++ b/PyMca5/PyMcaGraph/backends/MatplotlibBackend.py
@@ -1606,7 +1606,7 @@ def addCurve(self, x, y, legend=None, info=None, replace=False, replot=True,
                 scatterPlot = True
         if scatterPlot:
             # scatter plot
-            if color.dtype not in [numpy.float32, numpy.float]:
+            if color.dtype not in [numpy.float32, numpy.float64]:
                 actualColor = color / 255.
             else:
                 actualColor = color