diff --git a/src/libFLAC/include/private/bitmath.h b/src/libFLAC/include/private/bitmath.h
index ca73628..209bf68 100644
--- a/src/libFLAC/include/private/bitmath.h
+++ b/src/libFLAC/include/private/bitmath.h
@@ -78,10 +78,10 @@ static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v)
     return _bit_scan_reverse(v) ^ 31U;
 #elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
 /* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on
- * -march= setting or to a software rutine in exotic machines. */
+ * -march= setting or to a software routine in exotic machines. */
     return __builtin_clz(v);
 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
-    FLAC__uint32 idx;
+    unsigned long idx;
     _BitScanReverse(&idx, v);
     return idx ^ 31U;
 #else
@@ -122,45 +122,35 @@ static inline unsigned int FLAC__clz2_uint32(FLAC__uint32 v)
 
 static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
 {
+#if defined(__INTEL_COMPILER)
+    return _bit_scan_reverse(v);
+#elif defined(_MSC_VER) && (_MSC_VER >= 1400)
+    unsigned long idx;
+    _BitScanReverse(&idx, v);
+    return idx;
+#else
     return sizeof(FLAC__uint32) * CHAR_BIT  - 1 - FLAC__clz_uint32(v);
+#endif
 }
 
 
-#ifdef FLAC__INTEGER_ONLY_LIBRARY /*Unused otherwise */
+#ifdef FLAC__INTEGER_ONLY_LIBRARY /* Unused otherwise */
 
 static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
 {
-    if (v == 0)
-		return 0;
+/* Never used with input 0 */
 #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
     return sizeof(FLAC__uint64) * CHAR_BIT - 1 - __builtin_clzll(v);
 /* Sorry, only supported in win64/Itanium.. */
 #elif (defined(_MSC_VER) && (_MSC_VER >= 1400)) && (defined(_M_IA64) || defined(_WIN64))
-    FLAC__uint64 idx;
+    unsigned long idx;
     _BitScanReverse64(&idx, v);
-    return idx ^ 63U;
+    return idx;
 #else
-/* Brain-damaged compilers will use the fastest possible way that is,
-    de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf)
-    (C) Timothy B. Terriberry (tterribe@xiph.org) 2001-2009 LGPL (v2 or later).
-*/
-    static const unsigned char DEBRUIJN_IDX64[64]={
-        0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40,
-        5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57,
-        63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56,
-        62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58
-    };
-    int ret;
-    ret= v>0;
-    v|= v>>1;
-    v|= v>>2;
-    v|= v>>4;
-    v|= v>>8;
-    v|= v>>16;
-    v|= v>>32;
-    v= (v>>1)+1;
-    ret+=DEBRUIJN_IDX64[v*0x218A392CD3D5DBF>>58&0x3F];
-    return ret;
+     if (v>0xFFFFFFFFU)
+         return 32+FLAC__bitmath_ilog2((FLAC__uint32)(v>>32));
+     else
+         return FLAC__bitmath_ilog2((FLAC__uint32)v);
 #endif
 }
 #endif