diff --git a/source/utils/CarlaMutex.hpp b/source/utils/CarlaMutex.hpp
index a2069a79a..108378631 100644
--- a/source/utils/CarlaMutex.hpp
+++ b/source/utils/CarlaMutex.hpp
@@ -27,7 +27,7 @@ class CarlaSignal;
 // -----------------------------------------------------------------------
 // CarlaMutex class
 
-class CarlaMutex
+class CARLA_API CarlaMutex
 {
 public:
     /*
diff --git a/source/utils/CarlaString.hpp b/source/utils/CarlaString.hpp
index a0bff935e..8490c5c30 100644
--- a/source/utils/CarlaString.hpp
+++ b/source/utils/CarlaString.hpp
@@ -26,7 +26,7 @@
 // -----------------------------------------------------------------------
 // CarlaString class
 
-class CarlaString
+class CARLA_API CarlaString
 {
 public:
     // -------------------------------------------------------------------