diff --git a/HISTORY b/HISTORY
index 0547192e..e925bb41 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,6 +1,12 @@
 SnapRAID HISTORY
 ================
 
+8.1 2015/05
+===========
+ * Fix builds issues in generic Unix platforms.
+ * The "diff" command returns with error code 2 if a "sync" is
+   required, to differentiate with the generic error code 1.
+
 8.0 2015/04
 ===========
  * Allows "sync" and "scrub" to continue after the first bunch of disk
diff --git a/Makefile.am b/Makefile.am
index f1745904..dba84751 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -231,13 +231,13 @@ endif
 	echo DUP > bench/disk1/DUP2
 	echo --- Some commands with a not empty array
 # Run a sync using physical offset
-	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_PHYSICAL) -c $(CONF) --test-expect-failure diff > output.log
+	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_PHYSICAL) -c $(CONF) --test-expect-need-sync diff > output.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_PHYSICAL) -c $(CONF) sync
 # Now reset the array, as we normally test with alpha order and murmur3
 	rm bench/content bench/?-content
 # Now rebuild the array with alpha order and murmur3 and do some commands
 # Later we will convert it to spooky2 to test both hashes
-	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) --test-expect-failure  diff > output.log
+	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) --test-expect-need-sync  diff > output.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) -c $(CONF) --test-force-murmur3 --test-force-autosave-at 100 sync
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) dup -l test.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) list -l test.log > output.log
@@ -274,14 +274,14 @@ endif
 	rm bench/disk4/a/9*
 	rm bench/disk5/a/9*
 	rm bench/disk6/a/9*
-	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) --test-expect-failure diff > output.log
+	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) --test-expect-need-sync diff > output.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) sync -l test.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) -c $(CONF) check
 	echo --- Move some files, sync and check
 	mv bench/disk1/a/9* bench/disk4/a
 	mv bench/disk2/a/9* bench/disk5/a
 	mv bench/disk3/a/9* bench/disk6/a
-	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) --test-expect-failure diff > output.log
+	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(CONF) --test-expect-need-sync diff > output.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) -c $(CONF) sync
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) -c $(CONF) check
 	echo --- Create some more files, hardlinks and empty directories, delete others, sync PAR1 and check
@@ -303,7 +303,7 @@ endif
 	echo 333 > bench/disk3/file_hardlink1
 	ln bench/disk3/file_hardlink1 bench/disk3/file_hardlink2
 	ln bench/disk3/file_hardlink1 bench/disk3/file_hardlink3
-	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(PAR1) --test-expect-failure diff > output.log
+	$(FAILENV) ./snapraid$(EXEEXT) $(CHECKFLAGS_VERBOSE) -c $(PAR1) --test-expect-need-sync diff > output.log
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) --test-skip-fallocate -c $(PAR1) sync
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) -c $(CONF) status
 	$(TESTENV) ./snapraid$(EXEEXT) $(CHECKFLAGS) --test-skip-sequential -c $(PAR1) check
diff --git a/cmdline/mingw.c b/cmdline/mingw.c
index ee688ba5..f4cf3c1e 100644
--- a/cmdline/mingw.c
+++ b/cmdline/mingw.c
@@ -22,10 +22,11 @@
 #include "support.h"
 
 /**
- * Standard exit codes.
+ * Exit codes.
  */
 int exit_success = 0;
 int exit_failure = 1;
+int exit_sync_needed = 2;
 
 /* Adds missing Windows declaration */
 typedef struct _FILE_ATTRIBUTE_TAG_INFO {
diff --git a/cmdline/portable.h b/cmdline/portable.h
index a7ca6237..a6b91bd7 100644
--- a/cmdline/portable.h
+++ b/cmdline/portable.h
@@ -336,10 +336,12 @@ FILE* stdlog;
  */
 int exit_success;
 int exit_failure;
+int exit_sync_needed;
 #undef EXIT_SUCCESS
 #undef EXIT_FAILURE
 #define EXIT_SUCCESS exit_success
 #define EXIT_FAILURE exit_failure
+#define EXIT_SYNC_NEEDED exit_sync_needed
 
 /**
  * Fill memory with psudeo-random values.
diff --git a/cmdline/scan.c b/cmdline/scan.c
index 055cfed1..87a3e4a4 100644
--- a/cmdline/scan.c
+++ b/cmdline/scan.c
@@ -1748,11 +1748,11 @@ static int state_diffscan(struct snapraid_state* state, int is_diff)
 	if (is_diff) {
 		/* check for file difference */
 		if (!no_difference)
-			return -1;
+			return 1;
 
 		/* check also for incomplete "sync" */
 		if (parity_is_invalid(state))
-			return -1;
+			return 1;
 	}
 
 	return 0;
diff --git a/cmdline/snapraid.c b/cmdline/snapraid.c
index b3d86ef1..9d935812 100644
--- a/cmdline/snapraid.c
+++ b/cmdline/snapraid.c
@@ -245,6 +245,7 @@ void config(char* conf, size_t conf_size, const char* argv0)
 #define OPT_TEST_SKIP_DISK_ACCESS 282
 #define OPT_TEST_FORCE_AUTOSAVE_AT 283
 #define OPT_TEST_FAKE_DEVICE 284
+#define OPT_TEST_EXPECT_NEED_SYNC 285
 
 #if HAVE_GETOPT_LONG
 struct option long_options[] = {
@@ -338,6 +339,9 @@ struct option long_options[] = {
 	/* Exit generic failure */
 	{ "test-expect-failure", 0, 0, OPT_TEST_EXPECT_FAILURE },
 
+	/* Exit generic need sync */
+	{ "test-expect-need-sync", 0, 0, OPT_TEST_EXPECT_NEED_SYNC },
+
 	/* Run some command after loading the state and before the command */
 	{ "test-run", 1, 0, OPT_TEST_RUN },
 
@@ -675,10 +679,15 @@ int main(int argc, char* argv[])
 			opt.force_content_text = 1;
 			break;
 		case OPT_TEST_EXPECT_FAILURE :
-			/* invert the exit code */
+			/* invert the exit codes */
 			exit_success = 1;
 			exit_failure = 0;
 			break;
+		case OPT_TEST_EXPECT_NEED_SYNC :
+			/* invert the exit codes */
+			exit_success = 1;
+			exit_sync_needed = 0;
+			break;
 		case OPT_TEST_RUN :
 			run = optarg;
 			break;
@@ -975,12 +984,9 @@ int main(int argc, char* argv[])
 
 		ret = state_diff(&state);
 
-		/* abort if required */
-		if (ret != 0) {
-			/* LCOV_EXCL_START */
-			exit(EXIT_FAILURE);
-			/* LCOV_EXCL_STOP */
-		}
+		/* abort if sync needed */
+		if (ret > 0)
+			exit(EXIT_SYNC_NEEDED);
 	} else if (operation == OPERATION_SYNC) {
 
 		/* in the next state read ensures to clear all the past hashes in case */
diff --git a/cmdline/unix.c b/cmdline/unix.c
index c67a6f50..01c7c79c 100644
--- a/cmdline/unix.c
+++ b/cmdline/unix.c
@@ -22,10 +22,11 @@
 #include "support.h"
 
 /**
- * Standard exit codes.
+ * Exit codes.
  */
 int exit_success = 0;
 int exit_failure = 1;
+int exit_sync_needed = 2;
 
 int open_noatime(const char* file, int flags)
 {
diff --git a/snapraid.1 b/snapraid.1
index 7c8e4c58..74d96200 100644
--- a/snapraid.1
+++ b/snapraid.1
@@ -725,8 +725,8 @@ their parity data recomputed.
 This command doesn\'t check the file data, but only the file timestamp
 size and inode.
 .PP
-If a \[dq]sync\[dq] is not required, the return error code is 0. Otherwise,
-it\'s 1.
+If a \[dq]sync\[dq] is required, the process return code is 2, instead of the
+default 0. The return code 1 is instead for a generic error condition.
 .PP
 Nothing is modified.
 .SS sync 
diff --git a/snapraid.d b/snapraid.d
index bb6ea067..3508eb17 100644
--- a/snapraid.d
+++ b/snapraid.d
@@ -437,8 +437,8 @@ Commands
 	This command doesn't check the file data, but only the file timestamp
 	size and inode.
 
-	If a "sync" is not required, the return error code is 0. Otherwise,
-	it's 1.
+	If a "sync" is required, the process return code is 2, instead of the
+	default 0. The return code 1 is instead for a generic error condition.
 
 	Nothing is modified.
 
diff --git a/snapraid.txt b/snapraid.txt
index a110da35..5d32daa4 100644
--- a/snapraid.txt
+++ b/snapraid.txt
@@ -471,8 +471,8 @@ their parity data recomputed.
 This command doesn't check the file data, but only the file timestamp
 size and inode.
 
-If a "sync" is not required, the return error code is 0. Otherwise,
-it's 1.
+If a "sync" is required, the process return code is 2, instead of the
+default 0. The return code 1 is instead for a generic error condition.
 
 Nothing is modified.