diff --git a/modules/geom/src/vec3.hh b/modules/geom/src/vec3.hh
index 5283146a11840df78450a5ea960a00c374b35293..7c0d92046f93f727631a55ca95a4d1e4cfb42f8b 100644
--- a/modules/geom/src/vec3.hh
+++ b/modules/geom/src/vec3.hh
@@ -185,7 +185,7 @@ inline Vec3 operator/(Real d, const Vec3& v)
 
 inline std::ostream& operator<<(std::ostream& os, const Vec3& v)
 {
-  os << "[" << v.x << ", " << v.y << "]";
+  os << "[" << v.x << ", " << v.y << ", " << v.z << "]";
   return os;
 }
 }