diff --git a/tests/+matlab/+namespace/y_k.m b/tests/+matlab/+namespace/y_k.m
new file mode 100644
index 0000000000000000000000000000000000000000..7257ecd15ca97cce6e79682a6afdfa0faf10bf4c
--- /dev/null
+++ b/tests/+matlab/+namespace/y_k.m
@@ -0,0 +1,3 @@
+function retval = y_k(alpha, beta, delta)
+    retval = (1/alpha)*(1/beta-1+delta);
+end
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 38d0bdd2d2ab84f0f3518c65b9af14e80cffa038..a0f83811703a197873f4d74c24d22d6a7e3e5374 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -777,6 +777,7 @@ EXTRA_DIST = \
 	run_reporting_test_matlab.m \
 	run_reporting_test_octave.m \
 	run_all_unitary_tests.m \
+	+matlab/+namespace/y_k.m \
 	reporting/AnnualTable.m \
 	reporting/CommResidTablePage.m \
 	reporting/CountryGraphPage.m \
diff --git a/tests/walsh.mod b/tests/walsh.mod
index 606746ca10823202e355a6c0bf1ad69a8e5062aa..fced66cca6603eb9be11e8177c0720562093adeb 100644
--- a/tests/walsh.mod
+++ b/tests/walsh.mod
@@ -67,7 +67,7 @@ steady_state_model;
 // adapting solution Walsh (2003) p. 84
 en = 1/3;
 eR = 1/beta;
-y_k = (1/alpha)*(1/beta-1+delta);
+y_k = matlab.namespace.y_k(alpha, beta, delta);
 ek = en*y_k^(-1/(1-alpha));
 ec = ek*(y_k-delta);
 em = ec*(a/(1-a))^(-1/b)*((thetass-beta)/thetass)^(-1/b);