diff --git a/include/boost/fiber/fiber_manager.hpp b/include/boost/fiber/fiber_manager.hpp
index 43fcfd81..bcba2597 100644
--- a/include/boost/fiber/fiber_manager.hpp
+++ b/include/boost/fiber/fiber_manager.hpp
@@ -94,6 +94,7 @@ public:
 
     std::chrono::high_resolution_clock::duration wait_interval() noexcept;
 
+    bool preserve_fpu() const;
     void preserve_fpu( bool);
 };
 
diff --git a/src/fiber_manager.cpp b/src/fiber_manager.cpp
index 813802c7..3352b8c8 100644
--- a/src/fiber_manager.cpp
+++ b/src/fiber_manager.cpp
@@ -251,7 +251,7 @@ fiber_manager::wait_interval() noexcept {
 }
 
 bool
-fiber_manager::preserve_fpu() {
+fiber_manager::preserve_fpu() const {
     return preserve_fpu_;
 }