diff --git a/include/universal/number/qd/math/fractional.hpp b/include/universal/number/qd/math/fractional.hpp
index d1ef7f9da..637f03d73 100644
--- a/include/universal/number/qd/math/fractional.hpp
+++ b/include/universal/number/qd/math/fractional.hpp
@@ -9,12 +9,12 @@
 namespace sw { namespace universal {
 
 	// fmod retuns x - n*y where n = x/y with the fractional part truncated
-	qd fmod(qd x, qd y) {
+	qd fmod(const qd& x, const qd& y) {
 		return qd(std::fmod(double(x), double(y)));
 	}
 
 	// shim to stdlib
-	qd remainder(qd x, qd y) {
+	qd remainder(const qd& x, const qd& y) {
 		return qd(std::remainder(double(x), double(y)));
 	}
 
diff --git a/include/universal/number/qd/mathlib.hpp b/include/universal/number/qd/mathlib.hpp
index 2688a1559..47973b7e6 100644
--- a/include/universal/number/qd/mathlib.hpp
+++ b/include/universal/number/qd/mathlib.hpp
@@ -12,7 +12,7 @@
 //#include <universal/number/qd/math/complex.hpp>
 #include <universal/number/qd/math/error_and_gamma.hpp>
 #include <universal/number/qd/math/exponent.hpp>
-//#include <universal/number/qd/math/fractional.hpp>
+#include <universal/number/qd/math/fractional.hpp>
 //#include <universal/number/qd/math/hyperbolic.hpp>
 //#include <universal/number/qd/math/hypot.hpp>
 //#include <universal/number/qd/math/logarithm.hpp>
diff --git a/static/qd/math/fractional.cpp b/static/qd/math/fractional.cpp
new file mode 100644
index 000000000..7b94013bd
--- /dev/null
+++ b/static/qd/math/fractional.cpp
@@ -0,0 +1,106 @@
+// fractional.cpp: test suite runner for fractional functions for quad-double (qd) floating-point
+//
+// Copyright (C) 2017 Stillwater Supercomputing, Inc.
+// SPDX-License-Identifier: MIT
+//
+// This file is part of the universal numbers project, which is released under an MIT Open Source license.
+#include <universal/utility/directives.hpp>
+#include <numbers>
+#include <universal/number/qd/qd.hpp>
+#include <universal/verification/test_suite.hpp>
+
+namespace sw {
+	namespace universal {
+
+		template<typename Ty>
+		void GenerateTestCase(Ty fa, Ty fb) {
+			unsigned precision = 25;
+			unsigned width = 30;
+			Ty fref;
+			sw::universal::qd a, b, ref, v;
+			a = fa;
+			b = fb;
+			fref = std::remainder(fa, fb);
+			ref = fref;
+			v = sw::universal::remainder(a, b);
+			auto oldPrec = std::cout.precision();
+			std::cout << std::setprecision(precision);
+			std::cout << " -> remainder(" << fa << "," << fb << ") = " << std::setw(width) << fref << std::endl;
+			std::cout << " -> remainder( " << a << "," << b << ")  = " << v << '\n' << to_binary(v) << '\n';
+			std::cout << to_binary(ref) << "\n -> reference\n";
+			std::cout << (ref == v ? "PASS" : "FAIL") << std::endl << std::endl;
+			std::cout << std::setprecision(oldPrec);
+		}
+	}
+}
+
+
+// Regression testing guards: typically set by the cmake configuration, but MANUAL_TESTING is an override
+#define MANUAL_TESTING 1
+// REGRESSION_LEVEL_OVERRIDE is set by the cmake file to drive a specific regression intensity
+// It is the responsibility of the regression test to organize the tests in a quartile progression.
+//#undef REGRESSION_LEVEL_OVERRIDE
+#ifndef REGRESSION_LEVEL_OVERRIDE
+#undef REGRESSION_LEVEL_1
+#undef REGRESSION_LEVEL_2
+#undef REGRESSION_LEVEL_3
+#undef REGRESSION_LEVEL_4
+#define REGRESSION_LEVEL_1 1
+#define REGRESSION_LEVEL_2 1
+#define REGRESSION_LEVEL_3 1
+#define REGRESSION_LEVEL_4 1
+#endif
+
+int main()
+try {
+	using namespace sw::universal;
+	using std::fmod;
+
+	std::string test_suite  = "quad-double mathlib fractional function validation";
+	std::string test_tag    = "fmod/remainder";
+	bool reportTestCases    = false;
+	int nrOfFailedTestCases = 0;
+
+	ReportTestSuiteHeader(test_suite, reportTestCases);
+
+#if MANUAL_TESTING
+
+	double a{ 1.5 }, b{ 1.25 };
+	qd da(a), db(b);
+
+	std::cout << "fmod( " << a << ", " << b << ") = " << fmod(a, b) << '\n';
+	std::cout << "fmod( " << da << ", " << db << ") = " << fmod(da, db) << '\n';
+
+	std::cout << "remainder( " << a << ", " << b << ") = " << remainder(a, b) << '\n';
+	std::cout << "remainder( " << da << ", " << db << ") = " << remainder(da, db) << '\n';
+
+	ReportTestSuiteResults(test_suite, nrOfFailedTestCases);
+	return EXIT_SUCCESS;   // ignore errors
+#else
+
+
+	ReportTestSuiteResults(test_suite, nrOfFailedTestCases);
+	return (nrOfFailedTestCases > 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+
+#endif  // MANUAL_TESTING
+}
+catch (char const* msg) {
+	std::cerr << "Caught ad-hoc exception: " << msg << std::endl;
+	return EXIT_FAILURE;
+}
+catch (const sw::universal::universal_arithmetic_exception& err) {
+	std::cerr << "Caught unexpected universal arithmetic exception : " << err.what() << std::endl;
+	return EXIT_FAILURE;
+}
+catch (const sw::universal::universal_internal_exception& err) {
+	std::cerr << "Caught unexpected universal internal exception: " << err.what() << std::endl;
+	return EXIT_FAILURE;
+}
+catch (const std::runtime_error& err) {
+	std::cerr << "Caught runtime exception: " << err.what() << std::endl;
+	return EXIT_FAILURE;
+}
+catch (...) {
+	std::cerr << "Caught unknown exception" << std::endl;
+	return EXIT_FAILURE;
+}