diff --git a/autoAdjustHwloc.hpp b/autoAdjustHwloc.hpp
index d2039c0..325d9bc 100644
--- a/autoAdjustHwloc.hpp
+++ b/autoAdjustHwloc.hpp
@@ -3,6 +3,19 @@
 #include "console.h"
 #include <hwloc.h>
 
+/*
+ * compat_popcnt is adapted from public domain code by:
+ * Portable Snippets - https://gitub.com/nemequ/portable-snippets
+ * Created by Evan Nemerson <evan@nemerson.com>
+ */
+int compat_popcnt(size_t x) 
+{
+	x = x - ((x >> 1) & (size_t)~(size_t)0/3);
+	x = (x & (size_t)~(size_t)0/15*3) + ((x >> 2) & (size_t)~(size_t)0/15*3);
+	x = (x + (x >> 4)) & (size_t)~(size_t)0/255*15;
+	return (size_t)(x * ((size_t)~(size_t)0/255)) >> (sizeof(size_t) - 1) * 8;
+}
+
 #ifdef _WIN32
 #include <windows.h>
 #else
@@ -98,7 +111,7 @@ private:
 				cpu >>= rightZeros(allcpu);
 
 
-				int nativeCores = __builtin_popcount(cpu);
+				int nativeCores = compat_popcnt(cpu);
 				int numPus = obj->arity;
 				for (int i = 0; i < numPus && numHashes != 0; i++)
 				{