diff --git a/NEWS.md b/NEWS.md
index c825e9f16..ae7106872 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -86,6 +86,7 @@
 * The bundled `fmt` library was updated to v8.0.0.
 * The `PCRE2` & `JPCRE2` libraries are not used anymore. The bundled version
   of `JPCRE2` was removed.
+* The `gmp` library is now required.
 
 
 # Version 58.0.0 "Supper's Ready" 2021-06-13
diff --git a/Rakefile b/Rakefile
index ea27aae50..bc18c7c4c 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1066,6 +1066,7 @@ $common_libs = [
   :fmt,
   :stdcppfs,
   :qt_non_gui,
+  :gmp,
   "-lstdc++",
 ]
 
diff --git a/ac/boost.m4 b/ac/boost.m4
index bbb17f887..d31cab18f 100644
--- a/ac/boost.m4
+++ b/ac/boost.m4
@@ -1,9 +1,40 @@
 # boost's headers must be present.
 AX_BOOST_BASE([1.66.0])
 
-AX_BOOST_CHECK_HEADERS([boost/multiprecision/cpp_int.hpp],,[
-  AC_MSG_ERROR([Boost's multi-precision library is required but wasn't found])
-])
+AC_MSG_CHECKING([for Boost's multi-precision library with GMP backend])
+
+saved_CPPFLAGS="$CPPFLAGS"
+saved_LDFLAGS="$LDFLAGS"
+saved_LIBS="$LIBS"
+
+CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
+export CPPFLAGS
+LDFLAGS="$LDFLAGS $BOOST_LDFLAGS"
+export LDFLAGS
+LIBS="$LIBS -lgmp"
+export LIBS
+
+AC_LANG_PUSH(C++)
+
+AC_COMPILE_IFELSE([
+  AC_LANG_PROGRAM([[
+    #include <boost/multiprecision/gmp.hpp>
+  ]],
+  [[
+    boost::multiprecision::mpz_int i{42};
+    boost::multiprecision::mpq_rational r{42, 54};
+  ]])
+],[am_cv_bmp_gmp=yes],[am_cv_bmp_gmp=no])
+
+CPPFLAGS="$saved_CPPFLAGS"
+LDFLAGS="$saved_LDFLAGS"
+LIBS="$saved_LIBS"
+
+if test "x$am_cv_bmp_gmp" != xyes; then
+  AC_MSG_RESULT([no: a test program for Boost's multi-precision library with GMP backend could not be linked, probably because the gmp library wasn't found])
+  exit 1
+fi
+AC_MSG_RESULT([yes])
 
 AX_BOOST_CHECK_HEADERS([boost/operators.hpp],,[
   AC_MSG_ERROR([Boost's Operators library is required but wasn't found])
diff --git a/packaging/centos-fedora-opensuse/mkvtoolnix.spec b/packaging/centos-fedora-opensuse/mkvtoolnix.spec
index e93a05202..d72eeee79 100644
--- a/packaging/centos-fedora-opensuse/mkvtoolnix.spec
+++ b/packaging/centos-fedora-opensuse/mkvtoolnix.spec
@@ -20,6 +20,7 @@ BuildRequires: flac-devel
 BuildRequires: fmt-devel
 BuildRequires: gettext-devel
 BuildRequires: glibc-devel
+BuildRequires: gmp-devel
 BuildRequires: gtest-devel
 BuildRequires: libdvdread-devel
 BuildRequires: libogg-devel
diff --git a/packaging/debian/control b/packaging/debian/control
index 2e48e2150..f30af3d18 100644
--- a/packaging/debian/control
+++ b/packaging/debian/control
@@ -7,7 +7,7 @@ Standards-Version: 3.9.5
 Build-Depends:
  debhelper (>= 9),
  rake (>= 10),
- zlib1g-dev, libflac-dev, libogg-dev, libvorbis-dev,
+ zlib1g-dev, libflac-dev, libogg-dev, libvorbis-dev, libgmp-dev,
  libboost-dev (>= 1.66), qtbase5-dev, qtbase5-dev-tools,
  qtmultimedia5-dev, qt5-default | base-files (>= 11ubuntu18),
  libcmark-dev, libgtest-dev, libfmt-dev (>= 4), libdvdread-dev,
diff --git a/src/input/r_qtmp4.cpp b/src/input/r_qtmp4.cpp
index f01a0dd30..4ea045939 100644
--- a/src/input/r_qtmp4.cpp
+++ b/src/input/r_qtmp4.cpp
@@ -20,7 +20,7 @@
 #include <cstring>
 #include <unordered_map>
 
-#include <boost/multiprecision/cpp_int.hpp>
+#include <boost/multiprecision/gmp.hpp>
 
 #include <QRegularExpression>
 
@@ -2199,7 +2199,7 @@ qtmp4_demuxer_c::to_nsecs(int64_t value,
   if (!actual_time_scale)
     return 0;
 
-  auto value128  = static_cast<boost::multiprecision::int128_t>(value);
+  auto value128  = static_cast<boost::multiprecision::mpz_int>(value);
   value128      *= 1'000'000'000ll;
   value128      /= actual_time_scale;