diff --git a/configure.ac b/configure.ac
index 6e3e577..1a0df35 100644
--- a/configure.ac
+++ b/configure.ac
@@ -197,7 +197,7 @@
 
 dnl Check for mmap (needed by electricfence plugin)
 AC_FUNC_MMAP
-AC_CHECK_FUNCS([mmap64])
+AC_CHECK_SIZEOF([off_t])
 AM_CONDITIONAL(GST_HAVE_MMAP, test "x$ac_cv_func_mmap_fixed_mapped" = "xyes")
 
 dnl Check for mmap (needed by electricfence plugin)
diff --git a/meson.build b/meson.build
index ebae8cb..6c1868b 100644
--- a/meson.build
+++ b/meson.build
@@ -126,6 +126,7 @@
 cdata.set('SIZEOF_LONG', cc.sizeof('long'))
 cdata.set('SIZEOF_SHORT', cc.sizeof('short'))
 cdata.set('SIZEOF_VOIDP', cc.sizeof('void*'))
+cdata.set('SIZEOF_OFF_T', cc.sizeof('off_t'))
 
 # Here be fixmes.
 # FIXME: check if this is correct
diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 81abb5d..6c7a366 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -55,6 +55,10 @@
 
 #define ENCODED_BUFFER_SIZE             (2 * 1024 * 1024)
 
+#if SIZEOF_OFF_T == 8
+#define mmap64 mmap
+#endif
+
 enum
 {
   PROP_0,