diff --git a/extras/buildsystem/cmake/config.h.cmake b/extras/buildsystem/cmake/config.h.cmake
index 1665974aac8e773ec7ee56434f360997c8775369..c87dbf58d2a649c58e6846224eb7633826bbccf0 100644
--- a/extras/buildsystem/cmake/config.h.cmake
+++ b/extras/buildsystem/cmake/config.h.cmake
@@ -314,6 +314,9 @@
 #cmakedefine HAVE___FSETLOCKING
 #cmakedefine HAVE___VA_COPY
 #cmakedefine ICONV_CONST ${ICONV_CONST}
+#ifndef ICONV_CONST
+# define ICONV_CONST
+#endif
 #cmakedefine INTDIV0_RAISES_SIGFPE
 #cmakedefine LIBEXT "${LIBEXT}"
 #cmakedefine NDEBUG