diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 8a0b304382..4a0d2fb950 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -83,6 +83,12 @@
 #define FF_API_OLD_AUDIOCONVERT (LIBAVCODEC_VERSION_MAJOR < 53)
 #endif
 
+#if LIBAVCODEC_VERSION_MAJOR < 53
+#   define FF_INTERNALC_MEM_TYPE unsigned int
+#else
+#   define FF_INTERNALC_MEM_TYPE size_t
+#endif
+
 #define AV_NOPTS_VALUE          INT64_C(0x8000000000000000)
 #define AV_TIME_BASE            1000000
 #define AV_TIME_BASE_Q          (AVRational){1, AV_TIME_BASE}
@@ -4007,7 +4013,7 @@ AVBitStreamFilter *av_bitstream_filter_next(AVBitStreamFilter *f);
  *
  * @see av_realloc
  */
-void *av_fast_realloc(void *ptr, unsigned int *size, unsigned int min_size);
+void *av_fast_realloc(void *ptr, unsigned int *size, FF_INTERNALC_MEM_TYPE min_size);
 
 /**
  * Allocate a buffer, reusing the given one if large enough.
@@ -4021,7 +4027,7 @@ void *av_fast_realloc(void *ptr, unsigned int *size, unsigned int min_size);
  * @param min_size minimum size of *ptr buffer after returning, *ptr will be NULL and
  *                 *size 0 if an error occurred.
  */
-void av_fast_malloc(void *ptr, unsigned int *size, unsigned int min_size);
+void av_fast_malloc(void *ptr, unsigned int *size, FF_INTERNALC_MEM_TYPE min_size);
 
 #if LIBAVCODEC_VERSION_MAJOR < 53
 /**
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 4a713136a0..69d333eabc 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -48,29 +48,32 @@ static int volatile entangled_thread_counter=0;
 int (*ff_lockmgr_cb)(void **mutex, enum AVLockOp op);
 static void *codec_mutex;
 
-void *av_fast_realloc(void *ptr, unsigned int *size, unsigned int min_size)
+void *av_fast_realloc(void *ptr, unsigned int *size, FF_INTERNALC_MEM_TYPE min_size)
 {
     if(min_size < *size)
         return ptr;
 
-    *size= FFMAX(17*min_size/16 + 32, min_size);
+    min_size= FFMAX(17*min_size/16 + 32, min_size);
 
-    ptr= av_realloc(ptr, *size);
+    ptr= av_realloc(ptr, min_size);
     if(!ptr) //we could set this to the unmodified min_size but this is safer if the user lost the ptr and uses NULL now
-        *size= 0;
+        min_size= 0;
+
+    *size= min_size;
 
     return ptr;
 }
 
-void av_fast_malloc(void *ptr, unsigned int *size, unsigned int min_size)
+void av_fast_malloc(void *ptr, unsigned int *size, FF_INTERNALC_MEM_TYPE min_size)
 {
     void **p = ptr;
     if (min_size < *size)
         return;
-    *size= FFMAX(17*min_size/16 + 32, min_size);
+    min_size= FFMAX(17*min_size/16 + 32, min_size);
     av_free(*p);
-    *p = av_malloc(*size);
-    if (!*p) *size = 0;
+    *p = av_malloc(min_size);
+    if (!*p) min_size = 0;
+    *size= min_size;
 }
 
 /* encoder management */