diff --git a/msvc/include/exv_msvc.h b/msvc/include/exv_msvc.h
index c5036c2e..e7788202 100644
--- a/msvc/include/exv_msvc.h
+++ b/msvc/include/exv_msvc.h
@@ -53,6 +53,10 @@ typedef int pid_t;
 /* Define to 1 if you have the `iconv' function. */
 # undef EXV_HAVE_ICONV
 
+#ifdef  EXV_HAVE_ICONV
+#define EXV_ICONV_CONST const
+#endif
+
 /* Define as 1 if you have the `zlib' library. (0 to omit zlib) [png support] */
 #define HAVE_LIBZ 1
 
diff --git a/msvc64/include/exv_msvc.h b/msvc64/include/exv_msvc.h
index 4e315e28..9d22c5d6 100644
--- a/msvc64/include/exv_msvc.h
+++ b/msvc64/include/exv_msvc.h
@@ -53,6 +53,10 @@ typedef int pid_t;
 /* Define to 1 if you have the `iconv' function. */
 # undef EXV_HAVE_ICONV
 
+#ifdef  EXV_HAVE_ICONV
+#define EXV_ICONV_CONST const
+#endif
+
 /* Define as 1 if you have the `zlib' library. (0 to omit zlib) [png support] */
 #define HAVE_LIBZ 1