diff --git a/cutils.c b/cutils.c
index 142347d6acb..9f124f5ea32 100644
--- a/cutils.c
+++ b/cutils.c
@@ -95,3 +95,14 @@ time_t mktimegm(struct tm *tm)
     t += 3600 * tm->tm_hour + 60 * tm->tm_min + tm->tm_sec;
     return t;
 }
+
+int fls(int i)
+{
+    int bit;
+
+    for (bit=31; bit >= 0; bit--)
+        if (i & (1 << bit))
+            return bit+1;
+
+    return 0;
+}
diff --git a/qemu-common.h b/qemu-common.h
index 74eaa4dfc50..308847a21d0 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -94,6 +94,7 @@ char *pstrcat(char *buf, int buf_size, const char *s);
 int strstart(const char *str, const char *val, const char **ptr);
 int stristart(const char *str, const char *val, const char **ptr);
 time_t mktimegm(struct tm *tm);
+int fls(int i);
 
 #define qemu_isalnum(c)		isalnum((unsigned char)(c))
 #define qemu_isalpha(c)		isalpha((unsigned char)(c))