diff --git a/configure.ac b/configure.ac
index 1209fb6..4ed7f83 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,6 +43,8 @@ LT_INIT
 AM_CPPFLAGS="$CPPFLAGS"
 
 AC_CHECK_HEADERS([stdint.h])
+AC_CHECK_FUNCS([popcount64])
+
 AC_CHECK_PROGS([DOXYGEN], [doxygen])
 AM_CONDITIONAL([HAVE_DOXYGEN], [test -n "$DOXYGEN"])
 
diff --git a/libcpuid/libcpuid_util.c b/libcpuid/libcpuid_util.c
index f7a0868..9bed613 100644
--- a/libcpuid/libcpuid_util.c
+++ b/libcpuid/libcpuid_util.c
@@ -29,6 +29,9 @@
 #include <stdarg.h>
 #include <string.h>
 #include <ctype.h>
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
 #include "libcpuid.h"
 #include "libcpuid_util.h"
 
@@ -74,9 +77,10 @@ void debugf(int verboselevel, const char* format, ...)
 	_warn_fun(buff);
 }
 
-static int popcount64(uint64_t mask)
+#ifndef HAVE_POPCOUNT64
+static unsigned int popcount64(uint64_t mask)
 {
-	int num_set_bits = 0;
+	unsigned int num_set_bits = 0;
 
 	while (mask) {
 		mask &= mask - 1;
@@ -85,6 +89,7 @@ static int popcount64(uint64_t mask)
 
 	return num_set_bits;
 }
+#endif
 
 static int score(const struct match_entry_t* entry, const struct cpu_id_t* data,
                  int brand_code, uint64_t bits, int model_code)