diff --git a/src/fileio.c b/src/fileio.c
index 799439b1..f22ee8e0 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -72,6 +72,8 @@ char *fileio_fmtstr(FILEFMT format) {
     return "ELF";
   case FMT_IMM:
     return "in-place immediate";
+  case FMT_EEGG:
+    return "R-number list";
   case FMT_BIN:
     return "0b-binary byte list";
   case FMT_DEC:
@@ -101,6 +103,8 @@ int fileio_fmtchr(FILEFMT format) {
     return 'e';
   case FMT_IMM:
     return 'm';
+  case FMT_EEGG:
+    return 'R';
   case FMT_BIN:
     return 'b';
   case FMT_DEC:
@@ -114,7 +118,6 @@ int fileio_fmtchr(FILEFMT format) {
   }
 }
 
-
 FILEFMT fileio_format(char c) {
   switch (c) {
   case 'a':
@@ -131,6 +134,8 @@ FILEFMT fileio_format(char c) {
     return FMT_ELF;
   case 'm':
     return FMT_IMM;
+  case 'R':
+    return FMT_EEGG;
   case 'b':
     return FMT_BIN;
   case 'd':
@@ -149,6 +154,7 @@ typedef enum {
   LAST_SEG  = 2,
 } Segorder_t;
 
+
 static void print_ihex_extended_addr(int n_64k, FILE *outf) {
   unsigned char hi = (n_64k >> 8);
   unsigned char lo = n_64k;
@@ -1199,10 +1205,15 @@ static int b2num(const char *filename, FILE *f, const AVRMEM *mem, Segment_t *se
       prefix = "0b";
       base = 2;
       break;
+
+    case FMT_EEGG:
+      prefix = "";
+      base = 'r';
+      break;
   }
 
   for (int i = segp->addr; i < segp->addr + segp->len; i++) {
-    char cbuf[20];
+    char cbuf[81];
 
     if (i > 0) {
       if (putc(',', f) == EOF)
@@ -1218,7 +1229,7 @@ static int b2num(const char *filename, FILE *f, const AVRMEM *mem, Segment_t *se
       if (fputs(prefix, f) == EOF)
         goto writeerr;
     }
-   str_utoa(num, cbuf, base);
+    str_utoa(num, cbuf, base);
     if (fputs(cbuf, f) == EOF)
       goto writeerr;
   }
@@ -1601,6 +1612,7 @@ int fileio_segments(int oprwv, const char *filename, FILEFMT format,
     case FMT_DEC:
     case FMT_OCT:
     case FMT_BIN:
+    case FMT_EEGG:
       thisrc = fileio_num(&fio, fname, f, mem, seglist+i, format);
       break;
 
diff --git a/src/libavrdude.h b/src/libavrdude.h
index 8164e1a4..33d22f69 100644
--- a/src/libavrdude.h
+++ b/src/libavrdude.h
@@ -989,6 +989,7 @@ typedef enum {
   FMT_IHEX,
   FMT_RBIN,
   FMT_IMM,
+  FMT_EEGG,
   FMT_HEX,
   FMT_DEC,
   FMT_OCT,
diff --git a/src/strutil.c b/src/strutil.c
index 54fe5ff4..05d23eb2 100644
--- a/src/strutil.c
+++ b/src/strutil.c
@@ -310,6 +310,30 @@ char *str_utoa(unsigned n, char *buf, int base) {
   unsigned q;
   char *cp;
 
+  if(base == 'r') {
+    const char *units = "IVXLCDMFTYHSNabcdefghijkl";
+    const char *rep[10] = {"", "a", "aa", "aaa", "ab", "b", "ba", "baa", "baaa", "ac"};
+
+    if(n == 0) {
+      strcpy(buf, "0");
+      return buf;
+    }
+
+    int i = 0;
+    for(unsigned u = n; u; u /= 10)
+      i++;
+    for(*buf = 0; i > 0; i--) {
+      unsigned u = n;
+      for(int j=1; j<i; j++)
+        u /= 10;
+      char *q = buf+strlen(buf);
+      for(const char *p = rep[u%10], *d = units + (i-1)*2; *p; p++)
+        *q++ = d[*p-'a'];
+      *q = 0;
+    }
+    return buf;
+  }
+
   if(base < 2 || base > 36) {
     *buf = 0;
     return buf;