diff --git a/Core/include/Acts/Vertexing/Vertex.ipp b/Core/include/Acts/Vertexing/Vertex.ipp
index 2485121528a..8a85d64df4d 100644
--- a/Core/include/Acts/Vertexing/Vertex.ipp
+++ b/Core/include/Acts/Vertexing/Vertex.ipp
@@ -47,7 +47,7 @@ inline Acts::Vector4& Acts::Vertex::fullPosition() {
   return m_position;
 }
 
-inline const Acts::Vector4& Acts::Vertex::fullSeedPosition() {
+inline const Acts::Vector4& Acts::Vertex::fullSeedPosition() const {
   return m_seedPosition;
 }