diff --git a/qpms/vswf.c b/qpms/vswf.c
index e526ce8..2bc6660 100644
--- a/qpms/vswf.c
+++ b/qpms/vswf.c
@@ -308,7 +308,7 @@ qpms_errno_t qpms_vswf_fill_alternative(csphvec_t *const longtarget, csphvec_t *
   qpms_y_t nelem = qpms_lMax2nelem(lMax);
   csphvec_t *a;
   QPMS_CRASHING_MALLOC(a, 3*nelem*sizeof(csphvec_t))
-  csphvec_t * const a1 = a, * const a2 = a1 + nelem, * const a3 = a2 + 2 * nelem;
+  csphvec_t * const a1 = a, * const a2 = a1 + nelem, * const a3 = a1 + 2 * nelem;
   QPMS_ENSURE_SUCCESS(qpms_vecspharm_fill(a1, a2, a3, lMax, kr, norm));
   const csphvec_t *p1 = a1; 
   const csphvec_t *p2 = a2;
diff --git a/tests/catch/CMakeLists.txt b/tests/catch/CMakeLists.txt
index 287c600..6a82bca 100644
--- a/tests/catch/CMakeLists.txt
+++ b/tests/catch/CMakeLists.txt
@@ -1,5 +1,7 @@
 find_package(Catch2 REQUIRED)
-add_executable(catchtest all_includes.C)
-target_link_libraries(catchtest PRIVATE Catch2::Catch2WithMain qpms)
+add_executable(catchtest all_includes.C t_vswf.C catch_aux.C)
+# TODO ensure that the tests are linked against the "working tree" version of qpms,
+# not the installed one
+target_link_libraries(catchtest PRIVATE Catch2::Catch2WithMain qpms lapacke)
 
 
diff --git a/tests/catch/t_vswf.C b/tests/catch/t_vswf.C
new file mode 100644
index 0000000..118501e
--- /dev/null
+++ b/tests/catch/t_vswf.C
@@ -0,0 +1,44 @@
+#include <catch2/catch.hpp>
+#include <qpms_error.h>
+#include <vswf.h>
+#include "catch_aux.h"
+using namespace qpmstest;
+
+constexpr qpms_l_t lMax = 6;
+
+static std::vector<double> vswfvals_dvector(double r, double theta, double phi, 
+    qpms_l_t lMax, qpms_bessel_t btyp, qpms_normalisation_t norm) 
+{
+  std::vector<double> vals(2 /*el and mg for now */ * (lMax * (lMax+2)) 
+      * 3 /* 3D vector components */ * 2 /*for real and imag*/);
+  qpms_vswf_fill( 
+      nullptr, (csphvec_t *) &(vals[0]), (csphvec_t *) &(vals[(lMax*(lMax+2)) * 3 * 2]),
+      lMax, sph_t{r, theta, phi},
+      btyp, norm);
+  return vals;
+}
+
+static std::vector<double> vswfvals_dvector_alternative(double r, double theta, double phi, 
+    qpms_l_t lMax, qpms_bessel_t btyp, qpms_normalisation_t norm) 
+{
+  std::vector<double> vals(2 /*el and mg for now */ * (lMax * (lMax+2)) 
+      * 3 /* 3D vector components */ * 2 /*for real and imag*/);
+  qpms_vswf_fill_alternative( 
+      nullptr, (csphvec_t *) &(vals[0]), (csphvec_t *) &(vals[(lMax*(lMax+2)) * 3 * 2]),
+      lMax, sph_t{r, theta, phi},
+      btyp, norm);
+  return vals;
+}
+
+TEST_CASE("VSWF alternative implementation") {
+  using Catch::Matchers::Approx;
+  auto norms = GENERATE(QPMS_NORMALISATION_DEFAULT, QPMS_NORMALISATION_NORM_POWER,
+      QPMS_NORMALISATION_NORM_SPHARM, QPMS_NORMALISATION_CONVENTION_SCUFF);
+  auto thetas = GENERATE(0., M_PI_2, M_PI_2/2, M_PI, 3*M_PI_2, 0.1, -0.2, 4., 12.666);
+  auto phis = GENERATE(0., M_PI_2, M_PI_2/2, M_PI, 3*M_PI_2, 0.1, -0.2, 4., 12.666);
+  auto rs_positive = GENERATE(0.0001, 0.001, 0.01, 0.1, 1., 10., 100.);
+  CHECK_THAT( 
+        vswfvals_dvector(rs_positive, thetas, phis, lMax, QPMS_HANKEL_PLUS, norms),
+        Approx(vswfvals_dvector_alternative(rs_positive, thetas, phis, lMax, QPMS_HANKEL_PLUS, norms))
+      ) ;
+}