diff --git a/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/changelog b/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/changelog
index 6192237e..f0385efe 100644
--- a/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/changelog
+++ b/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/changelog
@@ -1,3 +1,10 @@
+mp4v2 (2.0.0~dfsg0-5~debian11.0.0+4~a) bullseye; urgency=medium
+
+  * debian/patches/: patchset updated
+    - 0006-Fix_FTBFS_with_cxx11.diff
+
+ -- Michele Calgaro <michele.calgaro@yahoo.it>  Fri, 23 Jul 2021 12:20:48 +0900
+
 mp4v2 (2.0.0~dfsg0-5~debian11.0.0+3~a) bullseye; urgency=medium
 
   * debian/patches/: patchset updated
diff --git a/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/0006-Fix_FTBFS_with_cxx11.diff b/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/0006-Fix_FTBFS_with_cxx11.diff
new file mode 100644
index 00000000..d73b1b85
--- /dev/null
+++ b/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/0006-Fix_FTBFS_with_cxx11.diff
@@ -0,0 +1,23 @@
+Fixed FTBFS caused by c++11.
+--- a/src/mp4.cpp
++++ b/src/mp4.cpp
+@@ -870,7 +870,7 @@
+         }
+ 
+         catch (...) {
+-            return MP4_INVALID_TRACK_ID;
++            return NULL;
+         }
+     }
+ 
+--- a/src/mp4util.h
++++ b/src/mp4util.h
+@@ -33,7 +33,7 @@
+ #ifndef ASSERT
+ #   define ASSERT(expr) \
+         if (!(expr)) { \
+-            throw new Exception("assert failure: "LIBMPV42_STRINGIFY((expr)), __FILE__, __LINE__, __FUNCTION__ ); \
++            throw new Exception("assert failure: " LIBMPV42_STRINGIFY((expr)), __FILE__, __LINE__, __FUNCTION__ ); \
+         }
+ #endif
+ 
diff --git a/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/series b/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/series
index b9231d74..0de0a03c 100644
--- a/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/series
+++ b/debian/mp4v2/mp4v2-2.0.0~dfsg0/debian/patches/series
@@ -3,3 +3,4 @@
 0003-Reproducible_build.patch
 0004-Fix_ftbfs_with_gcc7.diff
 0005-Fix_FTBFS_narrowing.diff
+0006-Fix_FTBFS_with_cxx11.diff