diff --git a/pkgs/development/libraries/libphonenumber/build-reproducibility.patch b/pkgs/development/libraries/libphonenumber/build-reproducibility.patch
new file mode 100644
index 00000000000..202370a80fc
--- /dev/null
+++ b/pkgs/development/libraries/libphonenumber/build-reproducibility.patch
@@ -0,0 +1,24 @@
+diff --git a/tools/cpp/src/cpp-build/generate_geocoding_data.cc b/tools/cpp/src/cpp-build/generate_geocoding_data.cc
+index 205947e831..1e628e2cd2 100644
+--- a/tools/cpp/src/cpp-build/generate_geocoding_data.cc
++++ b/tools/cpp/src/cpp-build/generate_geocoding_data.cc
+@@ -97,7 +97,8 @@ class DirEntry {
+   DirEntryKinds kind_;
+ };
+ 
+-// Lists directory entries in path. "." and ".." are excluded. Returns true on
++// Lists directory entries in path. "." and ".." are excluded. Entries are
++// returned in a consistent order to ensure reproducibility. Returns true on
+ // success.
+ bool ListDirectory(const string& path, vector<DirEntry>* entries) {
+   entries->clear();
+@@ -135,6 +136,9 @@ bool ListDirectory(const string& path, vector<DirEntry>* entries) {
+     }
+     entries->push_back(DirEntry(entry->d_name, kind));
+   }
++  std::sort(
++      entries->begin(), entries->end(),
++      [](const DirEntry& a, const DirEntry& b) { return a.name() < b.name(); });
+ }
+ 
+ // Returns true if s ends with suffix.
diff --git a/pkgs/development/libraries/libphonenumber/default.nix b/pkgs/development/libraries/libphonenumber/default.nix
index 1c6d355da42..a9b0df3304b 100644
--- a/pkgs/development/libraries/libphonenumber/default.nix
+++ b/pkgs/development/libraries/libphonenumber/default.nix
@@ -11,6 +11,11 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-xLxadSxVY3DjFDQrqj3BuOvdMaKdFSLjocfzovJCBB0=";
   };
 
+  patches = [
+    # Submitted upstream: https://github.com/google/libphonenumber/pull/2921
+    ./build-reproducibility.patch
+  ];
+
   nativeBuildInputs = [
     cmake
     pkg-config