diff --git a/MagickCore/quantize.c b/MagickCore/quantize.c
index f860aa7..cadabd9 100644
--- a/MagickCore/quantize.c
+++ b/MagickCore/quantize.c
@@ -1434,7 +1434,7 @@
   size_t
     number_threads;
 
-  number_threads=GetOpenMPMaximumThreads();
+  number_threads=GetMagickResourceLimit(ThreadResource);
   pixels=(RealPixelInfo **) AcquireQuantumMemory(number_threads,
     sizeof(*pixels));
   if (pixels == (RealPixelInfo **) NULL)