diff --git a/src/strings.cpp b/src/strings.cpp
index 6a1205d541..a88099fb73 100644
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -168,24 +168,6 @@ void CopyInDParam(const std::span<const StringParameterBackup> backup)
 	}
 }
 
-/**
- * Copy \a num string parameters from the global string parameter array to the \a backup.
- * @param backup The backup to write to.
- * @param num Number of string parameters to copy.
- */
-void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num)
-{
-	backup.resize(num);
-	for (size_t i = 0; i < backup.size(); i++) {
-		const char *str = _global_string_params.GetParamStr(i);
-		if (str != nullptr) {
-			backup[i] = str;
-		} else {
-			backup[i] = _global_string_params.GetParam(i);
-		}
-	}
-}
-
 /**
  * Copy parameters into StringParameterBackup for long-term storage.
  * @param backup The backup to write to.
@@ -207,26 +189,6 @@ void CopyOutDParam(std::vector<StringParameterBackup> &backup, StringParameters
 	}
 }
 
-/**
- * Checks whether the global string parameters have changed compared to the given backup.
- * @param backup The backup to check against.
- * @return True when the parameters have changed, otherwise false.
- */
-bool HaveDParamChanged(const std::vector<StringParameterBackup> &backup)
-{
-	bool changed = false;
-	for (size_t i = 0; !changed && i < backup.size(); i++) {
-		bool global_has_string = _global_string_params.GetParamStr(i) != nullptr;
-		if (global_has_string != backup[i].string.has_value()) return true;
-
-		if (global_has_string) {
-			changed = backup[i].string.value() != _global_string_params.GetParamStr(i);
-		} else {
-			changed = backup[i].data != _global_string_params.GetParam(i);
-		}
-	}
-	return changed;
-}
 
 static void StationGetSpecialString(StringBuilder &builder, StationFacility x);
 static void GetSpecialTownNameString(StringBuilder &builder, int ind, uint32_t seed);
diff --git a/src/strings_func.h b/src/strings_func.h
index 4cc208b991..4a495112a2 100644
--- a/src/strings_func.h
+++ b/src/strings_func.h
@@ -99,9 +99,7 @@ void SetDParamStr(size_t n, const std::string &str);
 void SetDParamStr(size_t n, std::string &&str);
 
 void CopyInDParam(const std::span<const StringParameterBackup> backup);
-void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num);
 void CopyOutDParam(std::vector<StringParameterBackup> &backup, class StringParameters &&params);
-bool HaveDParamChanged(const std::vector<StringParameterBackup> &backup);
 
 uint64_t GetDParam(size_t n);
 
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 53884be7d7..55b71946b9 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -7,7 +7,6 @@ add_test_files(
     mock_spritecache.cpp
     mock_spritecache.h
     string_func.cpp
-    strings_func.cpp
     test_main.cpp
     test_script_admin.cpp
     test_window_desc.cpp
diff --git a/src/tests/strings_func.cpp b/src/tests/strings_func.cpp
deleted file mode 100644
index dd70b0a365..0000000000
--- a/src/tests/strings_func.cpp
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * This file is part of OpenTTD.
- * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
- * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
- */
-
-/** @file strings_func.cpp Test functionality from strings_func. */
-
-#include "../stdafx.h"
-
-#include "../3rdparty/catch2/catch.hpp"
-
-#include "../strings_func.h"
-
-TEST_CASE("HaveDParamChanged")
-{
-	SetDParam(0, 0);
-	SetDParamStr(1, "some string");
-
-	std::vector<StringParameterBackup> backup;
-	CopyOutDParam(backup, 2);
-
-	CHECK(HaveDParamChanged(backup) == false);
-
-	/* A different parameter 0 (both string and numeric). */
-	SetDParam(0, 1);
-	CHECK(HaveDParamChanged(backup) == true);
-
-	SetDParamStr(0, "some other string");
-	CHECK(HaveDParamChanged(backup) == true);
-
-	/* Back to the original state, nothing should have changed. */
-	SetDParam(0, 0);
-	CHECK(HaveDParamChanged(backup) == false);
-
-	/* A different parameter 1 (both string and numeric). */
-	SetDParamStr(1, "some other string");
-	CHECK(HaveDParamChanged(backup) == true);
-
-	SetDParam(1, 0);
-	CHECK(HaveDParamChanged(backup) == true);
-
-	/* Back to the original state, nothing should have changed. */
-	SetDParamStr(1, "some string");
-	CHECK(HaveDParamChanged(backup) == false);
-
-	/* Changing paramter 2 should not have any effect, as the backup is only 2 long. */
-	SetDParam(2, 3);
-	CHECK(HaveDParamChanged(backup) == false);
-
-}