diff --git a/src/term.c b/src/term.c
index 36849da9..77da4a4d 100644
--- a/src/term.c
+++ b/src/term.c
@@ -332,7 +332,8 @@ static int cmd_write(PROGRAMMER * pgm, struct avrpart * p,
   char * e;
   int len, maxsize;
   char * memtype;
-  unsigned long addr, i;
+  long addr;
+  long i;
   unsigned char * buf;
   unsigned char b;
   int rc;
@@ -345,7 +346,7 @@ static int cmd_write(PROGRAMMER * pgm, struct avrpart * p,
       "Usage: write <memtype> <start addr> <data1> <data2> <dataN>\n"
       "       write <memtype> <start addr> <no. bytes> <data1> <dataN> <...>\n\n"
       "       Add a suffix to manually specify the size for each field:\n"
-      "       H/h/S/s: 16-bit, L/l: 32-bit, F/f: 32-bit float\n");
+      "       H/h/S/s: 16-bit, L/l: 32-bit, LL/ll: 6-bit, F/f: 32-bit float\n");
     return -1;
   }
 
@@ -403,43 +404,55 @@ static int cmd_write(PROGRAMMER * pgm, struct avrpart * p,
     return -1;
   }
 
-  // Union to represent the data to write to memory
-  union Data {
-    float f;
-    int32_t i;
-    uint8_t a[4];
+  // Structure related to data that is being written to memory
+  struct Data {
+    // Data info
+    int32_t bytes_grown;
+    uint8_t size;
+    bool is_float;
+    // Data union
+    union {
+      float f;
+      int64_t ll;
+      uint8_t a[8];
+    };
   } data;
 
-  int32_t bytes_grown = 0;
-  for (i = start_offset; i < len + start_offset - bytes_grown; i++) {
-    bool is_float = false;
-    uint8_t data_length = 0;
+  for (i = start_offset; i < len + start_offset - data.bytes_grown; i++) {
+    data.is_float = false;
+    data.size = 0;
 
     // Handle the next argument
     if (i < argc - start_offset + 3) {
       // Get suffix if present
-      char suffix = argv[i][strlen(argv[i]) - 1];
-      if ((suffix == 'F' || suffix == 'f' || suffix == 'L' || suffix == 'l') && \
-          strncmp(argv[i], "0x", 2) != 0) {
+      char suffix  = argv[i][strlen(argv[i]) - 1];
+      char lsuffix = argv[i][strlen(argv[i]) - 2];
+      if ((suffix == 'L' && lsuffix == 'L') || (suffix == 'l' && lsuffix == 'l')) {
+        argv[i][strlen(argv[i]) - 2] = '\0';
+        data.size = 8;
+      } else if (suffix == 'L' || suffix == 'l') {
         argv[i][strlen(argv[i]) - 1] = '\0';
-        data_length = 4;
+        data.size = 4;
+      } else if ((suffix == 'F' || suffix == 'f') && strncmp(argv[i], "0x", 2) != 0) {
+        argv[i][strlen(argv[i]) - 1] = '\0';
+        data.size = 4;
       } else if (suffix == 'H' || suffix == 'h' || suffix == 'S' || suffix == 's') {
         argv[i][strlen(argv[i]) - 1] = '\0';
-        data_length = 2;
+        data.size = 2;
       } else if (suffix == '\'') {
-        data_length = 1;
-      } 
+        data.size = 1;
+      }
       // Try integers
-      data.i = strtol(argv[i], &e, 0);
+      data.ll = strtoll(argv[i], &e, 0);
       if (*e || (e == argv[i])) {
         // Try float
         data.f = strtof(argv[i], &e);
-        is_float = true;
+        data.is_float = true;
         if (*e || (e == argv[i])) {
-          is_float = false;
+          data.is_float = false;
           // Try single character
           if (argv[i][0] == '\'') {
-            data.i = argv[i][1];
+            data.ll = argv[i][1];
           } else {
             avrdude_message(MSG_INFO, "\n%s (write): can't parse data \"%s\"\n",
                   progname, argv[i]);
@@ -449,30 +462,37 @@ static int cmd_write(PROGRAMMER * pgm, struct avrpart * p,
         }
       }
       // Print warning if data size might be ambiguous
-      if(!data_length && \
+      if(!data.size && \
         (((strncmp(argv[i], "0x", 2) == 0) && strlen(argv[i]) > 3) || \
-        (data.i > 0xFF && strlen(argv[i]) > 2))) {
+        (data.ll > 0xFF && strlen(argv[i]) > 2))) {
         avrdude_message(MSG_INFO, "Warning: no size suffix specified for \"%s\". "
                                   "Writing %d bytes\n",
                                   argv[i],
-                                  is_float || labs(data.i) > 0xFFFF ? 4 : \
-                                  labs(data.i) > 0x00FF ? 2 : 1);
+                                  llabs(data.ll) > 0xFFFFFFFF ? 8 :
+                                  llabs(data.ll) > 0x0000FFFF || data.is_float ? 4 : \
+                                  llabs(data.ll) > 0x000000FF ? 2 : 1);
       }
     }
-    buf[i - start_offset + bytes_grown]     = data.a[0];
-    if (is_float || labs(data.i) > 0x00FF || data_length >= 2)
-      buf[i - start_offset + ++bytes_grown] = data.a[1];
-    if (is_float || labs(data.i) > 0xFFFF || data_length >= 4) {
-      buf[i - start_offset + ++bytes_grown] = data.a[2];
-      buf[i - start_offset + ++bytes_grown] = data.a[3];
+    buf[i - start_offset + data.bytes_grown]     = data.a[0];
+    if (llabs(data.ll) > 0x000000FF || data.size >= 2 || data.is_float)
+      buf[i - start_offset + ++data.bytes_grown] = data.a[1];
+    if (llabs(data.ll) > 0x0000FFFF || data.size >= 4 || data.is_float) {
+      buf[i - start_offset + ++data.bytes_grown] = data.a[2];
+      buf[i - start_offset + ++data.bytes_grown] = data.a[3];
+    }
+    if (llabs(data.ll) > 0xFFFFFFFF || data.size == 8) {
+      buf[i - start_offset + ++data.bytes_grown] = data.a[4];
+      buf[i - start_offset + ++data.bytes_grown] = data.a[5];
+      buf[i - start_offset + ++data.bytes_grown] = data.a[6];
+      buf[i - start_offset + ++data.bytes_grown] = data.a[7];
     }
   }
 
   // When in "fill" mode, the maximum size is already predefined
   if (write_mode == WRITE_MODE_FILL)
-    bytes_grown = 0;
+    data.bytes_grown = 0;
 
-  if ((addr + len + bytes_grown) > maxsize) {
+  if ((addr + len + data.bytes_grown) > maxsize) {
     avrdude_message(MSG_INFO, "%s (write): selected address and # bytes exceed "
                     "range for %s memory\n",
                     progname, memtype);
@@ -480,7 +500,7 @@ static int cmd_write(PROGRAMMER * pgm, struct avrpart * p,
   }
 
   pgm->err_led(pgm, OFF);
-  for (werror=0, i=0; i < (len + bytes_grown); i++) {
+  for (werror=0, i=0; i < (len + data.bytes_grown); i++) {
     rc = avr_write_byte(pgm, p, mem, addr+i, buf[i]);
     if (rc) {
       avrdude_message(MSG_INFO, "%s (write): error writing 0x%02x at 0x%05lx, rc=%d\n",