diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index 0594e104bb..f43bcae91e 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -187,21 +187,28 @@ static inline unsigned int show_bits(GetBitContext *s, int n);
 
 #define CLOSE_READER(name, gb) (gb)->index = name ## _index
 
+#define UPDATE_CACHE_BE_EXT(name, gb, bits, dst_bits) name ## _cache = \
+    AV_RB ## bits((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) >> (bits - dst_bits)
+
+#define UPDATE_CACHE_LE_EXT(name, gb, bits, dst_bits) name ## _cache = \
+    (uint ## dst_bits ## _t)(AV_RL ## bits((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7))
+
+/* Using these two macros ensures that 32 bits are available. */
+# define UPDATE_CACHE_LE_32(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 64, 32)
+
+# define UPDATE_CACHE_BE_32(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 64, 32)
+
 # ifdef LONG_BITSTREAM_READER
 
-# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
-      AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
+# define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_32(name, (gb))
 
-# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
-      AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))
+# define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_32(name, (gb))
 
 #else
 
-# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
-      AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
+# define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 32, 32)
 
-# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
-      AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)
+# define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 32, 32)
 
 #endif
 
@@ -209,12 +216,14 @@ static inline unsigned int show_bits(GetBitContext *s, int n);
 #ifdef BITSTREAM_READER_LE
 
 # define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb)
+# define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_LE_32(name, (gb))
 
 # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num)
 
 #else
 
 # define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)
+# define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_BE_32(name, (gb))
 
 # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num)
 
@@ -414,15 +423,26 @@ static inline unsigned int get_bits_long(GetBitContext *s, int n)
     av_assert2(n>=0 && n<=32);
     if (!n) {
         return 0;
-    } else if (n <= MIN_CACHE_BITS) {
+    } else if ((!HAVE_FAST_64BIT || av_builtin_constant_p(n <= MIN_CACHE_BITS))
+               && n <= MIN_CACHE_BITS) {
         return get_bits(s, n);
     } else {
+#if HAVE_FAST_64BIT
+        unsigned tmp;
+        OPEN_READER(re, s);
+        UPDATE_CACHE_32(re, s);
+        tmp = SHOW_UBITS(re, s, n);
+        LAST_SKIP_BITS(re, s, n);
+        CLOSE_READER(re, s);
+        return tmp;
+#else
 #ifdef BITSTREAM_READER_LE
         unsigned ret = get_bits(s, 16);
         return ret | (get_bits(s, n - 16) << 16);
 #else
         unsigned ret = get_bits(s, 16) << (n - 16);
         return ret | get_bits(s, n - 16);
+#endif
 #endif
     }
 }