diff --git a/src/phoneExtraction.cpp b/src/phoneExtraction.cpp
index c5c9652..278f68b 100644
--- a/src/phoneExtraction.cpp
+++ b/src/phoneExtraction.cpp
@@ -9,6 +9,7 @@
 #include <format.h>
 #include <s3types.h>
 #include <regex>
+#include <gsl_util.h>
 
 extern "C" {
 #include <pocketsphinx.h>
@@ -116,7 +117,7 @@ void sphinxErrorCallback(void* user_data, err_lvl_t errorLevel, const char* form
 	// Create varArgs list
 	va_list args;
 	va_start(args, format);
-	auto _ = finally([&args]() { va_end(args); });
+	auto _ = gsl::finally([&args]() { va_end(args); });
 
 	// Format message
 	const int initialSize = 256;
diff --git a/src/tools.h b/src/tools.h
index 61cac9f..a19118e 100644
--- a/src/tools.h
+++ b/src/tools.h
@@ -7,30 +7,3 @@
 
 template<typename T>
 using lambda_unique_ptr = std::unique_ptr<T, std::function<void(T*)>>;
-
-// The following definitions are taken from https://github.com/Microsoft/GSL.
-
-// final_act allows you to ensure something gets run at the end of a scope
-template <class F>
-class final_act
-{
-public:
-	explicit final_act(F f) noexcept : f_(std::move(f)), invoke_(true) {}
-
-	final_act(final_act&& other) noexcept : f_(std::move(other.f_)), invoke_(other.invoke_) { other.invoke_ = false; }
-	final_act(const final_act&) = delete;
-	final_act& operator=(const final_act&) = delete;
-
-	~final_act() noexcept { if (invoke_) f_(); }
-
-private:
-	F f_;
-	bool invoke_;
-};
-
-// finally() - convenience function to generate a final_act
-template <class F>
-final_act<F> finally(const F &f) noexcept { return final_act<F>(f); }
-
-template <class F>
-final_act<F> finally(F &&f) noexcept { return final_act<F>(std::forward<F>(f)); }