diff --git a/core/base/src/TColor.cxx b/core/base/src/TColor.cxx
index 8017b2c99ddc8..e5084cc52f1f7 100644
--- a/core/base/src/TColor.cxx
+++ b/core/base/src/TColor.cxx
@@ -43,6 +43,7 @@ namespace {
 static Int_t   gHighestColorIndex = 0;   ///< Highest color index defined
 static Float_t gColorThreshold    = -1.; ///< Color threshold used by GetColor
 static Int_t   gDefinedColors     = 0;  ///< Number of defined colors.
+static Int_t gLastDefinedColors = 0; ///< Previous number of defined colors
 
 #define fgGrayscaleMode TColor__GrayScaleMode()
 #define fgPalette TColor__Palette()
@@ -1405,7 +1406,9 @@ Bool_t TColor::DefinedColors()
 {
    // After initialization gDefinedColors == 649. If it is bigger it means some new
    // colors have been defined
-   return (gDefinedColors-649 > 50);
+   Bool_t hasChanged = (gDefinedColors - gLastDefinedColors) > 50;
+   gLastDefinedColors = gDefinedColors;
+   return hasChanged;
 }
 
 ////////////////////////////////////////////////////////////////////////////////