diff --git a/gtsam/linear/JacobianFactor-inl.h b/gtsam/linear/JacobianFactor-inl.h
index 38e84609a..f391d4afd 100644
--- a/gtsam/linear/JacobianFactor-inl.h
+++ b/gtsam/linear/JacobianFactor-inl.h
@@ -62,7 +62,7 @@ namespace gtsam {
 
   /* ************************************************************************* */
   namespace internal {
-    static DenseIndex getColsJF(const std::pair<Key,Matrix>& p) {
+    static inline DenseIndex getColsJF(const std::pair<Key,Matrix>& p) {
       return p.second.cols();
     }