diff --git a/lzma_compress.c b/lzma_compress.c
index fe1729c..290b59a 100644
--- a/lzma_compress.c
+++ b/lzma_compress.c
@@ -31,8 +31,6 @@
 #include <allocator.h>
 
 #define	SZ_ERROR_DESTLEN	100
-#define	LZMA_MAX_DICT		(1 << 30)
-#define	LZMA_DICT_THRESH	(1 << 29)
 #define	LZMA_DEFAULT_DICT	(1 << 24)
 
 CLzmaEncProps *p = NULL;
@@ -73,12 +71,20 @@ lzma_init(void **data, int *level, ssize_t chunksize)
 			p->dictSize = 0;
 		}
 		/* Determine the fast bytes value. */
-		if (*level < 7)
+		if (*level < 7) {
 			p->fb = 32;
-		else if (*level < 10)
+
+		} else if (*level < 10) {
 			p->fb = 64;
-		else
+
+		} else if (*level < 13) {
+			p->fb = 64;
+			p->mc = 128;
+
+		} else {
 			p->fb = 128;
+			p->mc = 256;
+		}
 		p->level = *level;
 		LzmaEncProps_Normalize(p);
 		slab_cache_add(p->litprob_sz);
diff --git a/main.c b/main.c
index b12b9ca..4e828c8 100644
--- a/main.c
+++ b/main.c
@@ -819,7 +819,7 @@ start_compress(const char *filename, uint64_t chunksize, int level)
 			chunksize = sbuf.st_size;
 			nthreads = 1;
 		} else {
-			if (nthreads > sbuf.st_size / chunksize) {
+			if (nthreads == 0 || nthreads > sbuf.st_size / chunksize) {
 				nthreads = sbuf.st_size / chunksize;
 				if (sbuf.st_size % chunksize)
 					nthreads++;
diff --git a/rabin/rabin_polynomial.c b/rabin/rabin_polynomial.c
index 1b4ada7..6a8f0eb 100755
--- a/rabin/rabin_polynomial.c
+++ b/rabin/rabin_polynomial.c
@@ -92,7 +92,7 @@ rabin_context_t *
 create_rabin_context(uint64_t chunksize, uint64_t real_chunksize, const char *algo) {
 	rabin_context_t *ctx;
 	unsigned char *current_window_data;
-	uint32_t blknum, index;
+	uint32_t blknum;
 	int level = 14;
 
 	/*