diff --git a/configure.in b/configure.in
index 9d6b7b93..e18814fc 100644
--- a/configure.in
+++ b/configure.in
@@ -56,7 +56,6 @@ AC_TYPE_SIZE_T
 
 dnl checks for structures
 AC_STRUCT_TM
-AC_CHECK_TYPES(mbstate_t,,,[#include <cwchar>])
 
 dnl checks for compiler characteristics
 AC_CHECK_SIZEOF(char, 1)
diff --git a/lib/io/CUnicode.cpp b/lib/io/CUnicode.cpp
index 0fe85dc3..040159f5 100644
--- a/lib/io/CUnicode.cpp
+++ b/lib/io/CUnicode.cpp
@@ -75,19 +75,11 @@ setError(bool* errors)
 //
 
 #if WINDOWS_LIKE
-#define HAVE_MBSTATE_T 1
 #define HAVE_MBSINIT 1
 #define HAVE_MBRTOWC 1
 #define HAVE_WCRTOMB 1
 #endif
 
-#if !HAVE_MBSTATE_T
-struct mbstate_t { int m_dummy; };
-#undef HAVE_MBSINIT
-#undef HAVE_MBRTOWC
-#undef HAVE_WCRTOMB
-#endif
-
 #if !HAVE_MBSINIT
 static
 int