diff --git a/lib/hweight.c b/lib/hweight.c
index 4382576..360556a 100644
--- a/lib/hweight.c
+++ b/lib/hweight.c
@@ -1,5 +1,6 @@
 #include <linux/module.h>
 #include <asm/types.h>
+#include <asm/bitops.h>
 
 /**
  * hweightN - returns the hamming weight of a N-bit word
@@ -40,14 +41,19 @@
 #if BITS_PER_LONG == 32
 	return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
 #elif BITS_PER_LONG == 64
+#ifdef ARCH_HAS_FAST_MULTIPLIER
+	w -= (w >> 1) & 0x5555555555555555ul;
+	w =  (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
+	w =  (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
+	return (w * 0x0101010101010101ul) >> 56;
+#else
 	__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
 	res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
 	res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
 	res = res + (res >> 8);
 	res = res + (res >> 16);
 	return (res + (res >> 32)) & 0x00000000000000FFul;
-#else
-#error BITS_PER_LONG not defined
+#endif
 #endif
 }
 EXPORT_SYMBOL(hweight64);