diff --git a/c/GLib_bcb/mylib/mylib.h b/c/GLib_bcb/mylib/mylib.h
index c7a7ae1..e75e2f9 100644
--- a/c/GLib_bcb/mylib/mylib.h
+++ b/c/GLib_bcb/mylib/mylib.h
@@ -1,5 +1,6 @@
 #if defined __cplusplus
-extern "C" {
+extern "C"
+{
 #endif
   void
   another_one (void);
diff --git a/c/cmake_static_lib/libmean/mean.c b/c/cmake_static_lib/libmean/mean.c
index dee9b7c..e4d580e 100644
--- a/c/cmake_static_lib/libmean/mean.c
+++ b/c/cmake_static_lib/libmean/mean.c
@@ -1,5 +1,7 @@
 //#include <stdio.h>
+#define __DLL_MEAN__
+#include "mean.h"
 
-double mean(double a, double b) {
+double DLL_SPEC mean(double a, double b) {
   return (a+b) / 2;
 }
diff --git a/c/cmake_static_lib/libmean/mean.h b/c/cmake_static_lib/libmean/mean.h
index 0822889..5df4d3d 100644
--- a/c/cmake_static_lib/libmean/mean.h
+++ b/c/cmake_static_lib/libmean/mean.h
@@ -1 +1,17 @@
-double mean(double, double);
+#if defined(__DLL_MEAN__)
+	#define DLL_SPEC __declspec(dllexport)
+#else
+	#define DLL_SPEC __declspec(dllimport)
+#endif
+
+
+#if defined __cplusplus
+extern "C"
+{
+#endif
+
+double DLL_SPEC mean(double, double);
+
+#if defined __cplusplus
+}
+#endif