diff --git a/matrix/filter.hpp b/matrix/filter.hpp
index 53fc99d92a..d075fc0f01 100644
--- a/matrix/filter.hpp
+++ b/matrix/filter.hpp
@@ -5,7 +5,7 @@
 namespace matrix {
 
 template<typename Type, size_t M, size_t N>
-void kalman_correct(
+int kalman_correct(
     const SquareMatrix<Type, M> & P,
     const Matrix<Type, N, M> & C,
     const SquareMatrix<Type, N> & R,
@@ -20,6 +20,7 @@ void kalman_correct(
     dx = K*r;
     beta = Scalar<Type>(r.T()*S_I*r);
     dP = K*C*P*(-1);
+    return 0;
 }
 
 }; // namespace matrix
diff --git a/test/filter.cpp b/test/filter.cpp
index b3b137cdcd..3470e5f4d4 100644
--- a/test/filter.cpp
+++ b/test/filter.cpp
@@ -5,7 +5,15 @@
 
 using namespace matrix;
 
-template class Vector<float, 5>;
+template int kalman_correct<float, 6, 5>(
+    const SquareMatrix<float, 6> & P,
+    const Matrix<float, 5, 6> & C,
+    const SquareMatrix<float, 5> & R,
+    const Vector<float, 5> &r,
+    Vector<float, 6> & dx,
+    SquareMatrix<float, 6> & dP,
+    float & beta
+);
 
 int main()
 {
diff --git a/test/integration.cpp b/test/integration.cpp
index e8b3889420..c1dea3b81d 100644
--- a/test/integration.cpp
+++ b/test/integration.cpp
@@ -5,6 +5,14 @@
 
 using namespace matrix;
 
+// instantiate template to ensure coverage check
+template int integrate_rk4<float, 6>(
+    Vector<float, 6> (*f)(float, Vector<float, 6>),
+    Vector<float, 6> & y,
+    float & t,
+    float h
+);
+
 Vector<float, 6> f(float t, Vector<float, 6> y);
 
 Vector<float, 6> f(float t, Vector<float, 6> y) {
diff --git a/test/vector2.cpp b/test/vector2.cpp
index e1d122fbde..d9c63ed71f 100644
--- a/test/vector2.cpp
+++ b/test/vector2.cpp
@@ -5,7 +5,7 @@
 
 using namespace matrix;
 
-template class Vector<float, 3>;
+template class Vector<float, 2>;
 
 int main()
 {