diff --git a/os/getw.h b/os/getw.h
index 0a2fc8859..b2574b0d4 100644
--- a/os/getw.h
+++ b/os/getw.h
@@ -1,4 +1,19 @@
 
+#define utf_cont(ch)  (((ch) & 0xc0) == 0x80)
+
+#define encoding_error(ch,v,st) post_process_read_wchar(1, v, st)
+
+static int post_process_f_weof(StreamDesc *st)
+{
+  if (ferror(st->file)) {
+    clearerr(st->file);
+    return 1;
+  } else {
+    return post_process_weof(st);
+  }
+    
+}
+
 /// compose a wide char from a sequence of getchars
 ///  this is a slow lane routine, called if no specialised code
 ///  isavailable.
@@ -7,20 +22,20 @@ extern int get_wchar(int sno) {
   int ch = st->stream_getc(sno);
 
   if (ch == -1)
-    return post_process_weof(st);
+    return post_process_f_weof(st);
 
   switch (st->encoding) {
   case ENC_OCTET:
-  // no error detection, all characters are ok.
+    // no error detection, all characters are ok.
   case ENC_ISO_LATIN1:
     return post_process_read_wchar(ch, 1, st);
-  // 7 bits code, anything above is bad news
+    // 7 bits code, anything above is bad news
   case ENC_ISO_ASCII:
     if (ch & 0x80) {
       /* error */
     }
     return post_process_read_wchar(ch, 1, st);
-  // default OS encoding, depends on locale.
+    // default OS encoding, depends on locale.
   case ENC_ISO_ANSI: {
     char buf[8];
     int out;
@@ -38,7 +53,7 @@ extern int get_wchar(int sno) {
     }
     return post_process_read_wchar(wch, n, st);
   }
-  // UTF-8 works o 8 bits.
+    // UTF-8 works o 8 bits.
   case ENC_ISO_UTF8: {
     int wch;
     unsigned char buf[8];
@@ -46,28 +61,36 @@ extern int get_wchar(int sno) {
     if (ch < 0x80) {
       return post_process_read_wchar(ch, 1, st);
     }
-    // if ((ch - 0xc2) > (0xf4-0xc2)) return UTF8PROC_ERROR_INVALIDUTF8;
+    if ((ch - 0xc2) > (0xf4-0xc2)) {
+      return encoding_error(ch, 1, st);
+    }
     if (ch < 0xe0) { // 2-byte sequence
                      // Must have valid continuation character
       int c1 = buf[0] = st->stream_getc(sno);
       if (c1 == -1)
         return post_process_weof(st);
-      // if (!utf_cont(*str)) return UTF8PROC_ERROR_INVALIDUTF8;
+      if (!utf_cont(c1)) {
+	return encoding_error(ch, 2, st);
+      }
       wch = ((ch & 0x1f) << 6) | (c1 & 0x3f);
       return post_process_read_wchar(wch, 2, st);
     }
     if (ch < 0xf0) { // 3-byte sequence
-      // if ((str + 1 >= end) || !utf_cont(*str) || !utf_cont(str[1]))
-      //   return UTF8PROC_ERROR_INVALIDUTF8;
-      // Check for surrogate chars
-      // if (ch == 0xed && *str > 0x9f)
-      //    return UTF8PROC_ERROR_INVALIDUTF8;
       int c1 = st->stream_getc(sno);
       if (c1 == -1)
         return post_process_weof(st);
+      //    return UTF8PROC_ERROR_INVALIDUTF8;
+      if (ch == 0xed && c1 > 0x9f) {
+        return encoding_error(ch, 1, st);
+      }
       int c2 = st->stream_getc(sno);
       if (c2 == -1)
         return post_process_weof(st);
+      if ( !utf_cont(c1) || !utf_cont(c2)) {
+	return encoding_error(ch, 2, st);
+	// Check for surrogate chars
+    
+      }
       wch = ((ch & 0xf) << 12) | ((c1 & 0x3f) << 6) | (c2 & 0x3f);
       return post_process_read_wchar(wch, 3, st);
     } else {
@@ -80,8 +103,11 @@ extern int get_wchar(int sno) {
       int c3 = st->stream_getc(sno);
       if (c3 == -1)
         return post_process_weof(st);
+      if ( !utf_cont(c1) || !utf_cont(c2) || !utf_cont(c3)) {
+	return encoding_error(ch, 3, st);
+      }
       wch = ((ch & 7) << 18) | ((c1 & 0x3f) << 12) | ((c2 & 0x3f) << 6) |
-            (c3 & 0x3f);
+	(c3 & 0x3f);
       return post_process_read_wchar(wch, 4, st);
     }
   }
@@ -208,7 +234,6 @@ extern int get_wchar(int sno) {
 extern int get_wchar_UTF8(int sno) {
   StreamDesc *st = GLOBAL_Stream + sno;
   int ch = st->stream_getc(sno);
-
   if (ch == -1)
     return post_process_weof(st);
   else {
@@ -224,7 +249,9 @@ extern int get_wchar_UTF8(int sno) {
       int c1 = buf[0] = st->stream_getc(sno);
       if (c1 == -1)
         return post_process_weof(st);
-      // if (!utf_cont(*str)) return UTF8PROC_ERROR_INVALIDUTF8;
+      if (!utf_cont(c1)) {
+	return encoding_error(ch, 2, st);
+      }
       wch = ((ch & 0x1f) << 6) | (c1 & 0x3f);
       return post_process_read_wchar(wch, 2, st);
     }
@@ -237,23 +264,31 @@ extern int get_wchar_UTF8(int sno) {
       int c1 = st->stream_getc(sno);
       if (c1 == -1)
         return post_process_weof(st);
+      if (ch == 0xed && c1 > 0x9f)
+         return  encoding_error(ch, 2, st);
       int c2 = st->stream_getc(sno);
       if (c2 == -1)
         return post_process_weof(st);
-      wch = ((ch & 0xf) << 12) | ((c1 & 0x3f) << 6) | (c2 & 0x3f);
+     wch = ((ch & 0xf)<<12) | ((c1 & 0x3f)<<6) | (c2 & 0x3f);
+     if (wch < 0x800)
+         return encoding_error(ch, 3, st);
       return post_process_read_wchar(wch, 3, st);
     } else {
       int c1 = st->stream_getc(sno);
       if (c1 == -1)
-        return post_process_weof(st);
+	return post_process_weof(st);
       int c2 = st->stream_getc(sno);
       if (c2 == -1)
-        return post_process_weof(st);
+	return post_process_weof(st);
       int c3 = st->stream_getc(sno);
       if (c3 == -1)
-        return post_process_weof(st);
-      wch = ((ch & 7) << 18) | ((c1 & 0x3f) << 12) | ((c2 & 0x3f) << 6) |
-            (c3 & 0x3f);
+	return post_process_weof(st);
+   if (ch == 0xf0) {
+    if (c1 < 0x90) return  encoding_error(ch, 4, st);
+  } else if (c1 == 0xf4) {
+    if (c2 > 0x8f) return  encoding_error(ch, 4, st);
+  }
+   wch = ((ch & 7)<<18) | ((c1 & 0x3f)<<12) | ((c2 & 0x3f)<<6) | (c3 & 0x3f);
       return post_process_read_wchar(wch, 4, st);
     }
   }