diff --git a/debian/changelog b/debian/changelog
index 295b4b60..a9d5d7d8 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+llvm-toolchain-13 (1:13.0.0~+rc1-2) UNRELEASED; urgency=medium
+
+  * clang-soname-extract-version.diff: improve the upstream declaration
+
+ -- Sylvestre Ledru <sylvestre@debian.org>  Thu, 19 Aug 2021 18:13:56 +0200
+
 llvm-toolchain-13 (1:13.0.0~+rc1-1) unstable; urgency=medium
 
   * Upload to Unstable
diff --git a/debian/patches/clang-soname-extract-version.diff b/debian/patches/clang-soname-extract-version.diff
new file mode 100644
index 00000000..34b365f7
--- /dev/null
+++ b/debian/patches/clang-soname-extract-version.diff
@@ -0,0 +1,22 @@
+Index: llvm-toolchain-13_13.0.0~++20210730102409+6eaf46beb462/clang/tools/libclang/CMakeLists.txt
+===================================================================
+--- llvm-toolchain-13_13.0.0~++20210730102409+6eaf46beb462.orig/clang/tools/libclang/CMakeLists.txt
++++ llvm-toolchain-13_13.0.0~++20210730102409+6eaf46beb462/clang/tools/libclang/CMakeLists.txt
+@@ -48,6 +48,8 @@ set(LIBS
+   clangTooling
+ )
+ 
++SET(CLANG_SONAME 13)
++
+ if (CLANG_ENABLE_ARCMT)
+   list(APPEND LIBS clangARCMigrate)
+ endif ()
+@@ -171,7 +173,7 @@ if(ENABLE_SHARED)
+     # LLVM_VERSION_MAJOR.
+     set_target_properties(libclang PROPERTIES
+                           VERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}${LLVM_VERSION_SUFFIX}
+-                          SOVERSION 13)
++                          SOVERSION ${CLANG_SONAME})
+   endif()
+ endif()
+ 
diff --git a/debian/patches/series b/debian/patches/series
index 6d9ac220..23b66509 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -142,3 +142,4 @@ lld-use-link-atomic-i386.diff
 lower-python-dep.diff
 scan-build-py-fix-analyze-path.diff
 scan-build-py-fix-default-bin.diff
+clang-soname-extract-version.diff