diff --git a/include/openssl/mirdef.h b/include/openssl/mirdef.h
index 4ce88d50..f4de7bda 100644
--- a/include/openssl/mirdef.h
+++ b/include/openssl/mirdef.h
@@ -3,6 +3,13 @@
  *   For C++ build of library
  */
 
+#ifndef HEADER_MIRDEF_H
+#define HEADER_MIRDEF_H
+
+#ifdef __cplusplus
+extern "C"{
+#endif
+
 #define MR_LITTLE_ENDIAN
 #define MIRACL 64
 #define mr_utype long
@@ -14,3 +21,9 @@
 #define MAXBASE ((mr_small)1<<(MIRACL-1))
 #define MR_BITSINCHAR 8
 #define MR_CPP
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif