diff --git a/matrix/SquareMatrix.hpp b/matrix/SquareMatrix.hpp
index 0457a03b1f..ddb059840d 100644
--- a/matrix/SquareMatrix.hpp
+++ b/matrix/SquareMatrix.hpp
@@ -241,7 +241,7 @@ bool inv(const SquareMatrix<Type, M> & A, SquareMatrix<Type, M> & inv)
     //check sanity of results
     for (size_t i = 0; i < M; i++) {
         for (size_t j = 0; j < M; j++) {
-            if (!isfinite(P(i,j))) {
+            if (!is_finite(P(i,j))) {
                 return false;
             }
         }
diff --git a/matrix/helper_functions.hpp b/matrix/helper_functions.hpp
index 7e0fd4bff4..893f4da492 100644
--- a/matrix/helper_functions.hpp
+++ b/matrix/helper_functions.hpp
@@ -14,7 +14,7 @@ namespace matrix
 {
 
 template<typename Type>
-bool isfinite(Type x) {
+bool is_finite(Type x) {
 #if defined (__PX4_NUTTX) || defined (__PX4_QURT)
     return PX4_ISFINITE(x);
 #else
@@ -25,7 +25,7 @@ bool isfinite(Type x) {
 template<typename Type>
 Type wrap_pi(Type x)
 {
-    if (!isfinite(x)) {
+    if (!is_finite(x)) {
         return x;
     }
 
diff --git a/matrix/math.hpp b/matrix/math.hpp
index 4a759efe63..b69d2e0eec 100644
--- a/matrix/math.hpp
+++ b/matrix/math.hpp
@@ -13,4 +13,3 @@
 #include "Scalar.hpp"
 #include "Quaternion.hpp"
 #include "AxisAngle.hpp"
-#include "helper_functions.hpp"