diff --git a/common/mathlib.cc b/common/mathlib.cc
index c56c20fa..a4129e3b 100644
--- a/common/mathlib.cc
+++ b/common/mathlib.cc
@@ -599,6 +599,17 @@ std::pair<int, qvec3f> GLM_ClosestPointOnPolyBoundary(const std::vector<qvec3f>
 
 std::pair<bool, qvec3f> GLM_InterpolateNormal(
     const std::vector<qvec3f> &points, const std::vector<face_normal_t> &normals, const qvec3f &point)
+{
+    std::vector<qvec3f> normalvecs;
+    for (auto& normal : normals) {
+        normalvecs.push_back(normal.normal);
+    }
+
+    return GLM_InterpolateNormal(points, normalvecs, point);
+}
+
+std::pair<bool, qvec3f> GLM_InterpolateNormal(
+    const std::vector<qvec3f> &points, const std::vector<qvec3f> &normals, const qvec3f &point)
 {
     Q_assert(points.size() == normals.size());
 
@@ -608,14 +619,14 @@ std::pair<bool, qvec3f> GLM_InterpolateNormal(
     // Step through the triangles, being careful to handle zero-size ones
 
     const qvec3f &p0 = points.at(0);
-    const qvec3f &n0 = normals.at(0).normal;
+    const qvec3f &n0 = normals.at(0);
 
     const int N = points.size();
     for (int i = 2; i < N; i++) {
         const qvec3f &p1 = points.at(i - 1);
-        const qvec3f &n1 = normals.at(i - 1).normal;
+        const qvec3f &n1 = normals.at(i - 1);
         const qvec3f &p2 = points.at(i);
-        const qvec3f &n2 = normals.at(i).normal;
+        const qvec3f &n2 = normals.at(i);
 
         const auto edgeplanes = GLM_MakeInwardFacingEdgePlanes({p0, p1, p2});
         if (edgeplanes.size() != 3)
diff --git a/include/common/mathlib.hh b/include/common/mathlib.hh
index 21dd3f72..53baa1f6 100644
--- a/include/common/mathlib.hh
+++ b/include/common/mathlib.hh
@@ -304,6 +304,8 @@ std::pair<int, qvec3f> GLM_ClosestPointOnPolyBoundary(const std::vector<qvec3f>
 /// Returns `true` and the interpolated normal if `point` is in the polygon, otherwise returns false.
 std::pair<bool, qvec3f> GLM_InterpolateNormal(
     const std::vector<qvec3f> &points, const std::vector<face_normal_t> &normals, const qvec3f &point);
+std::pair<bool, qvec3f> GLM_InterpolateNormal(
+    const std::vector<qvec3f> &points, const std::vector<qvec3f> &normals, const qvec3f &point);
 std::vector<qvec3f> GLM_ShrinkPoly(const std::vector<qvec3f> &poly, const float amount);
 /// Returns (front part, back part)
 std::pair<std::vector<qvec3f>, std::vector<qvec3f>> GLM_ClipPoly(const std::vector<qvec3f> &poly, const qvec4f &plane);
diff --git a/light/test_light.cc b/light/test_light.cc
index c2ceb6e7..2a8de6d0 100644
--- a/light/test_light.cc
+++ b/light/test_light.cc
@@ -282,7 +282,7 @@ TEST(mathlib, DistAbovePlane)
 
 TEST(mathlib, InterpolateNormalsDegenerate)
 {
-    EXPECT_FALSE(GLM_InterpolateNormal({}, {}, qvec3f(0, 0, 0)).first);
+    EXPECT_FALSE(GLM_InterpolateNormal({}, std::vector<qvec3f>{}, qvec3f(0, 0, 0)).first);
     EXPECT_FALSE(GLM_InterpolateNormal({qvec3f(0, 0, 0)}, {qvec3f(0, 0, 1)}, qvec3f(0, 0, 0)).first);
     EXPECT_FALSE(
         GLM_InterpolateNormal({qvec3f(0, 0, 0), qvec3f(10, 0, 0)}, {qvec3f(0, 0, 1), qvec3f(0, 0, 1)}, qvec3f(0, 0, 0))