diff --git a/src/avr.c b/src/avr.c
index d6e78bb5..a8945d86 100644
--- a/src/avr.c
+++ b/src/avr.c
@@ -439,16 +439,16 @@ int avr_read(PROGRAMMER * pgm, AVRPART * p, char * memtype,
 	(vmem->tags[i] & TAG_ALLOCATED) != 0)
     {
       rc = pgm->read_byte(pgm, p, mem, i, mem->buf + i);
-      if (rc != 0) {
+      if (rc != LIBAVRDUDE_SUCCESS) {
         avrdude_message(MSG_INFO, "avr_read(): error reading address 0x%04lx\n", i);
-        if (rc == -1) {
+        if (rc == LIBAVRDUDE_GENERAL_FAILURE) {
           avrdude_message(MSG_INFO, "    read operation not supported for memory \"%s\"\n",
                           memtype);
-          return -2;
+          return LIBAVRDUDE_NOTSUPPORTED;
         }
         avrdude_message(MSG_INFO, "    read operation failed for memory \"%s\"\n",
                         memtype);
-        return rc;
+        return LIBAVRDUDE_SOFTFAIL;
       }
     }
     report_progress(i, mem->size, NULL);
@@ -1035,14 +1035,14 @@ int avr_signature(PROGRAMMER * pgm, AVRPART * p)
 
   report_progress (0,1,"Reading");
   rc = avr_read(pgm, p, "signature", 0);
-  if (rc < 0) {
+  if (rc < LIBAVRDUDE_SUCCESS) {
     avrdude_message(MSG_INFO, "%s: error reading signature data for part \"%s\", rc=%d\n",
                     progname, p->desc, rc);
     return rc;
   }
   report_progress (1,1,NULL);
 
-  return 0;
+  return LIBAVRDUDE_SUCCESS;
 }
 
 static uint8_t get_fuse_bitmask(AVRMEM * m) {
diff --git a/src/jtag3.c b/src/jtag3.c
index 6d358dfa..23df86ff 100644
--- a/src/jtag3.c
+++ b/src/jtag3.c
@@ -313,6 +313,16 @@ static void jtag3_prmsg(PROGRAMMER * pgm, unsigned char * data, size_t len)
   }
 }
 
+static int jtag3_errcode(int status)
+{
+  if (status >= LIBAVRDUDE_SUCCESS)
+    return status;
+  if (status == RSP3_FAIL_OCD_LOCKED ||
+      status == RSP3_FAIL_CRC_FAILURE)
+    return LIBAVRDUDE_SOFTFAIL;
+  return LIBAVRDUDE_GENERAL_FAILURE;
+}
+
 static void jtag3_prevent(PROGRAMMER * pgm, unsigned char * data, size_t len)
 {
   int i;
@@ -850,7 +860,7 @@ int jtag3_recv(PROGRAMMER * pgm, unsigned char **msg) {
       putc('\n', stderr);
     avrdude_message(MSG_NOTICE2, "%s: %s command: timeout/error communicating with programmer (status %d)\n",
                     progname, descr, status);
-    return -1;
+    return LIBAVRDUDE_GENERAL_FAILURE;
   } else if (verbose >= 3) {
     putc('\n', stderr);
     jtag3_prmsg(pgm, *resp, status);
@@ -871,10 +881,11 @@ int jtag3_recv(PROGRAMMER * pgm, unsigned char **msg) {
     status = (*resp)[3];
     free(*resp);
     resp = 0;
-    return -status;
+
+    return jtag3_errcode(status);
   }
 
-  return status;
+  return LIBAVRDUDE_SUCCESS;
 }
 
 
@@ -987,10 +998,10 @@ static int jtag3_program_enable(PROGRAMMER * pgm)
     free(resp);
     PDATA(pgm)->prog_enabled = 1;
 
-    return 0;
+    return LIBAVRDUDE_SUCCESS;
   }
 
-  return status;
+  return jtag3_errcode(status);
 }
 
 static int jtag3_program_disable(PROGRAMMER * pgm)
@@ -1921,7 +1932,7 @@ static int jtag3_read_byte(PROGRAMMER * pgm, AVRPART * p, AVRMEM * mem,
 
   if (!(pgm->flag & PGM_FL_IS_DW))
     if ((status = jtag3_program_enable(pgm)) < 0)
-      return status;
+      return jtag3_errcode(status);
 
   cmd[0] = SCOPE_AVR;
   cmd[1] = CMD3_READ_MEMORY;
@@ -2007,7 +2018,7 @@ static int jtag3_read_byte(PROGRAMMER * pgm, AVRPART * p, AVRMEM * mem,
 
     if (addr == 0) {
       if ((status = jtag3_command(pgm, cmd, 12, &resp, "read memory")) < 0)
-	return status;
+	return jtag3_errcode(status);
 
       signature_cache[0] = resp[4];
       signature_cache[1] = resp[5];
@@ -2057,7 +2068,7 @@ static int jtag3_read_byte(PROGRAMMER * pgm, AVRPART * p, AVRMEM * mem,
   }
 
   if ((status = jtag3_command(pgm, cmd, 12, &resp, "read memory")) < 0)
-    return status;
+    return jtag3_errcode(status);
 
   if (resp[1] != RSP3_DATA ||
       status < (pagesize? pagesize: 1) + 4) {
@@ -2185,7 +2196,7 @@ static int jtag3_write_byte(PROGRAMMER * pgm, AVRPART * p, AVRMEM * mem,
   cmd[13] = data;
 
   if ((status = jtag3_command(pgm, cmd, 14, &resp, "write memory")) < 0)
-    return status;
+    return jtag3_errcode(status);
 
   free(resp);
 
@@ -2316,7 +2327,7 @@ int jtag3_read_sib(PROGRAMMER * pgm, AVRPART * p, char * sib)
   u32_to_b4(cmd + 8, AVR_SIBLEN);
 
   if ((status = jtag3_command(pgm, cmd, 12, &resp, "read SIB")) < 0)
-	return status;
+	return jtag3_errcode(status);
 
   memcpy(sib, resp+3, AVR_SIBLEN);
   sib[AVR_SIBLEN] = 0; // Zero terminate string
diff --git a/src/jtag3_private.h b/src/jtag3_private.h
index a3e7fb08..6385aa4c 100644
--- a/src/jtag3_private.h
+++ b/src/jtag3_private.h
@@ -145,6 +145,7 @@
 #  define RSP3_FAIL_UNSUPP_MEMORY       0x34 /* unsupported memory type */
 #  define RSP3_FAIL_WRONG_LENGTH        0x35 /* wrong lenth for mem access */
 #  define RSP3_FAIL_OCD_LOCKED          0x44 /* device is locked */
+#  define RSP3_FAIL_CRC_FAILURE         0x47 /* CRC failure in device */
 #  define RSP3_FAIL_NOT_UNDERSTOOD      0x91
 
 /* ICE events */
diff --git a/src/libavrdude.h b/src/libavrdude.h
index ddb72b48..46789f4f 100644
--- a/src/libavrdude.h
+++ b/src/libavrdude.h
@@ -27,6 +27,16 @@
 #include <stdint.h>
 
 typedef uint32_t pinmask_t;
+/*
+ * Values returned by library functions.
+ * Some library functions also return a count, i.e. a positive
+ * number greater than 0.
+ */
+#define LIBAVRDUDE_SUCCESS 0
+#define LIBAVRDUDE_GENERAL_FAILURE (-1)
+#define LIBAVRDUDE_NOTSUPPORTED (-2) // operation not supported
+#define LIBAVRDUDE_SOFTFAIL (-3) // returned by avr_signature() if caller
+                                 // might proceed with chip erase
 
 /* formerly lists.h */
 
diff --git a/src/main.c b/src/main.c
index 253c6e51..5b0a6e38 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1116,9 +1116,8 @@ int main(int argc, char * argv [])
     usleep(waittime);
     if (init_ok) {
       rc = avr_signature(pgm, p);
-      if (rc != 0) {
-        // -68 == -(0x44) == -(RSP3_FAIL_OCD_LOCKED)
-        if ((rc == -68) && (p->flags & AVRPART_HAS_UPDI) && (attempt < 1)) {
+      if (rc != LIBAVRDUDE_SUCCESS) {
+        if ((rc == LIBAVRDUDE_SOFTFAIL) && (p->flags & AVRPART_HAS_UPDI) && (attempt < 1)) {
           attempt++;
           if (pgm->read_sib) {
              // Read SIB and compare FamilyID