diff --git a/TODO b/TODO
index f43d284..c4daa01 100644
--- a/TODO
+++ b/TODO
@@ -44,6 +44,7 @@ Z85 headers:
    is marked as to be ignored which could be saved as a state when using
    blockmode.
 
+Check is_utf8 license.
 
 Python binding, e.g.:
 py % cdll.LoadLibrary("libsodium.so.8")
diff --git a/include/pcp/z85.h b/include/pcp/z85.h
index a82e3b6..2257788 100644
--- a/include/pcp/z85.h
+++ b/include/pcp/z85.h
@@ -57,7 +57,7 @@ we pad the input with zeroes and remove them after decoding.
 
     \return Returns a pointer to the padded data.
  */
-unsigned char *pcp_padfour(unsigned char *src, size_t srclen, size_t *dstlen);
+byte *pcp_padfour(byte *src, size_t srclen, size_t *dstlen);
 
 
 /** Unpad padded input data.
@@ -70,7 +70,7 @@ unsigned char *pcp_padfour(unsigned char *src, size_t srclen, size_t *dstlen);
 
     \return Returns the unpadded size of the data.
  */
-size_t pcp_unpadfour(unsigned char *src, size_t srclen);
+size_t pcp_unpadfour(byte *src, size_t srclen);
 
 /** Decode data from Z85 encoding.
 
@@ -83,7 +83,7 @@ size_t pcp_unpadfour(unsigned char *src, size_t srclen);
             returns NULL. Check fatals_if_any().
 
 */
-unsigned char *pcp_z85_decode(char *z85block, size_t *dstlen);
+byte *pcp_z85_decode(char *z85block, size_t *dstlen);
 
 
 /** Encode data to Z85 encoding.
@@ -96,7 +96,7 @@ unsigned char *pcp_z85_decode(char *z85block, size_t *dstlen);
 
     \return Returns a string (char array) containing the Z85 encoded data.
 */
-char *pcp_z85_encode(unsigned char *raw, size_t srclen, size_t *dstlen);
+char *pcp_z85_encode(byte *raw, size_t srclen, size_t *dstlen);
 
 /** Read a Z85 encoded file.
 
@@ -120,7 +120,21 @@ char *pcp_readz85file(FILE *infile);
     \return Raw Z85 encoded string with comments, headers and newlines removed.
 
  */
-char *pcp_readz85string(unsigned char *input, size_t bufsize);
+char *pcp_readz85string(byte *input, size_t bufsize);
+
+/** Check if a binary array is utf8.
+
+    Based on http://stackoverflow.com/questions/1031645/how-to-detect-utf-8-in-plain-c
+    by Christoph Gärtner
+
+    Modified to only check for one utf8 char. The given sequence must have
+    at least 4 bytes length. No boundary checks are being made.
+
+    \param[in] bytes A byte sequence with 4 or more bytes length.
+
+    \return Returns 0 if the sequence is not utf8 or a number greater than 1 indicating the size of the utf8 char.
+*/
+uint8_t is_utf8(const byte * string);
 
 /** Determine if a buffer is binary or ascii.
 
@@ -129,7 +143,7 @@ char *pcp_readz85string(unsigned char *input, size_t bufsize);
     \return Returns 0 if the input is ascii or a number > 0 if
             it contains binary data.
 */
-size_t _buffer_is_binary(unsigned char *buf, size_t len);
+size_t _buffer_is_binary(byte *buf, size_t len);
 
 
 /** Determine if a char is a Z85 character
diff --git a/libpcp/z85.c b/libpcp/z85.c
index 5ab75dd..f795511 100644
--- a/libpcp/z85.c
+++ b/libpcp/z85.c
@@ -22,19 +22,102 @@
 
 #include "z85.h"
 
-size_t _buffer_is_binary(unsigned char *buf, size_t len) {
+uint8_t is_utf8(const byte *bytes) {
+  if( (// non-overlong 2-byte
+       (0xC2 <= bytes[0] && bytes[0] <= 0xDF) &&
+       (0x80 <= bytes[1] && bytes[1] <= 0xBF)
+       )
+      ) {
+    return 2;
+  }
+  
+  if( (// excluding overlongs
+       bytes[0] == 0xE0 &&
+       (0xA0 <= bytes[1] && bytes[1] <= 0xBF) &&
+       (0x80 <= bytes[2] && bytes[2] <= 0xBF)
+       ) ||
+      (// straight 3-byte
+       ((0xE1 <= bytes[0] && bytes[0] <= 0xEC) ||
+	bytes[0] == 0xEE ||
+	bytes[0] == 0xEF) &&
+       (0x80 <= bytes[1] && bytes[1] <= 0xBF) &&
+       (0x80 <= bytes[2] && bytes[2] <= 0xBF)
+       ) ||
+      (// excluding surrogates
+       bytes[0] == 0xED &&
+       (0x80 <= bytes[1] && bytes[1] <= 0x9F) &&
+       (0x80 <= bytes[2] && bytes[2] <= 0xBF)
+       )
+      ) {
+    return 3;
+  }
+
+  if( (// planes 1-3
+       bytes[0] == 0xF0 &&
+       (0x90 <= bytes[1] && bytes[1] <= 0xBF) &&
+       (0x80 <= bytes[2] && bytes[2] <= 0xBF) &&
+       (0x80 <= bytes[3] && bytes[3] <= 0xBF)
+       ) ||
+      (// planes 4-15
+       (0xF1 <= bytes[0] && bytes[0] <= 0xF3) &&
+       (0x80 <= bytes[1] && bytes[1] <= 0xBF) &&
+       (0x80 <= bytes[2] && bytes[2] <= 0xBF) &&
+       (0x80 <= bytes[3] && bytes[3] <= 0xBF)
+       ) ||
+      (// plane 16
+       bytes[0] == 0xF4 &&
+       (0x80 <= bytes[1] && bytes[1] <= 0x8F) &&
+       (0x80 <= bytes[2] && bytes[2] <= 0xBF) &&
+       (0x80 <= bytes[3] && bytes[3] <= 0xBF)
+       )
+      ) {
+    return 4;
+  }
+
+  return 0;
+}
+
+size_t _buffer_is_binary(byte *buf, size_t len) {
   size_t pos;
+  byte wide[4] = {0};
+  uint8_t utf = 0;
+  int i;
+
   /* start at 1, to circumvent returning 0 if we find a match at position 0,
      which would lead the caller to believe the buffer is not binary */
   for (pos=1; pos<len; ++pos) {
     if(buf[pos] == '\0' || (buf[pos] != '\r' && buf[pos] != '\n' && isprint(buf[pos]) == 0)) {
-      break;
+      /* it's probably a binary char */
+
+      /* check for utf8 */
+      wide[0] = buf[pos];
+      for(i=1; i<3; i++) {
+	/* check for 2, 3 or 4 byte utf8 char */
+	if(pos+i < len) {
+	  /* only if there's enough space of course */
+	  wide[i] = buf[pos+i];
+	  if(is_utf8(wide) > 1) {
+	    pos += i; /* jump over the utf we already found */
+	    utf = 1;
+	  }
+	}
+	else 
+	  break;
+      }
+
+      if(utf == 1) {
+	/* it's a utf8 char, continue checking, reset wide */
+	memset(wide, 0, 4);
+	continue;
+      }
+
+      break; /* if we reach this, then it's binary and not utf8, stop checking */
     }
   }
   if(pos < len)
-    return pos;
+    return pos; /* binary */
   else
-    return 0;
+    return 0; /* text */
 }
 
 uint8_t _parse_zchar(Buffer *z, uint8_t c, uint8_t is_comment) {
@@ -52,15 +135,15 @@ uint8_t _parse_zchar(Buffer *z, uint8_t c, uint8_t is_comment) {
   return is_comment;
 }
 
-unsigned char *pcp_padfour(unsigned char *src, size_t srclen, size_t *dstlen) {
+byte *pcp_padfour(byte *src, size_t srclen, size_t *dstlen) {
   size_t outlen, zerolen;
-  unsigned char *dst;
+  byte *dst;
  
   outlen = srclen;
   while (outlen % 4 != 0) outlen++;
   zerolen = outlen - srclen;
 
-  dst = (unsigned char*)ucmalloc(outlen);
+  dst = (byte*)ucmalloc(outlen);
   memcpy(dst, src, srclen); /*  add the original */
   memset(&dst[srclen], 0, zerolen); /*  pad with zeroes  */
 
@@ -69,7 +152,7 @@ unsigned char *pcp_padfour(unsigned char *src, size_t srclen, size_t *dstlen) {
   return dst;
 }
 
-size_t pcp_unpadfour(unsigned char *src, size_t srclen) {
+size_t pcp_unpadfour(byte *src, size_t srclen) {
   size_t outlen;
   size_t i;
 
@@ -85,8 +168,8 @@ size_t pcp_unpadfour(unsigned char *src, size_t srclen) {
   return outlen;
 }
 
-unsigned char *pcp_z85_decode(char *z85block, size_t *dstlen) {
-  unsigned char *bin = NULL;
+byte *pcp_z85_decode(char *z85block, size_t *dstlen) {
+  byte *bin = NULL;
   size_t binlen, outlen; 
 
   binlen = strlen(z85block) * 4 / 5; 
@@ -104,12 +187,12 @@ unsigned char *pcp_z85_decode(char *z85block, size_t *dstlen) {
   return bin;
 }
 
-char *pcp_z85_encode(unsigned char *raw, size_t srclen, size_t *dstlen) {
+char *pcp_z85_encode(byte *raw, size_t srclen, size_t *dstlen) {
   int pos = 0;
   size_t outlen, blocklen, zlen;
 
   /*  make z85 happy (size % 4) */
-  unsigned char *padded = pcp_padfour(raw, srclen, &outlen);
+  byte *padded = pcp_padfour(raw, srclen, &outlen);
 
   /*  encode to z85 */
   zlen = (outlen * 5 / 4) + 1;
@@ -146,10 +229,10 @@ char *pcp_z85_encode(unsigned char *raw, size_t srclen, size_t *dstlen) {
 
 
 char *pcp_readz85file(FILE *infile) {
-  unsigned char *input = NULL;
-  unsigned char *tmp = NULL;
+  byte *input = NULL;
+  byte *tmp = NULL;
   size_t bufsize = 0;
-  unsigned char byte[1];
+  byte byte[1];
 
   while(!feof(infile)) {
     if(!fread(&byte, 1, 1, infile))
@@ -171,7 +254,7 @@ char *pcp_readz85file(FILE *infile) {
   return pcp_readz85string(input, bufsize);
 }
 
-char *pcp_readz85string(unsigned char *input, size_t bufsize) {
+char *pcp_readz85string(byte *input, size_t bufsize) {
   int i;
   size_t MAXLINE = 1024;