--- opencv/src/highgui/cvcap_ffmpeg.cpp
+++ opencv/src/highgui/cvcap_ffmpeg.cpp
@@ -49,6 +49,15 @@
 #if !defined(WIN32) || defined(__MINGW32__)
 // some versions of FFMPEG assume a C99 compiler, and don't define INT64_C
-#ifndef INT64_C
-#define INT64_C
+#if !defined INT64_C || !defined UINT64_C
+# if __WORDSIZE == 64
+#  define INT64_C(c)	c ## UL
+# else
+#  define INT64_C(c)	c ## ULL
+# endif
+# if __WORDSIZE == 64
+#  define UINT64_C(c)	c ## UL
+# else
+#  define UINT64_C(c)	c ## ULL
+# endif
 #define __STDC_CONSTANT_MACROS
 // force re-inclusion of stdint.h to get INT64_C macro
