diff --git a/count-delta.c b/count-delta.c
index 978a60ca9d..058a2aadb1 100644
--- a/count-delta.c
+++ b/count-delta.c
@@ -16,11 +16,7 @@
  *
  * Number of bytes that are _not_ copied from the source is deletion,
  * and number of inserted literal bytes are addition, so sum of them
- * is the extent of damage.  xdelta can express an edit that copies
- * data inside of the destination which originally came from the
- * source.  We do not count that in the following routine, so we are
- * undercounting the source material that remains in the final output
- * that way.
+ * is the extent of damage.
  */
 int count_delta(void *delta_buf, unsigned long delta_size,
 		unsigned long *src_copied, unsigned long *literal_added)
diff --git a/delta.h b/delta.h
index 31d1820f80..a15350dabc 100644
--- a/delta.h
+++ b/delta.h
@@ -19,14 +19,14 @@ extern void *patch_delta(void *src_buf, unsigned long src_size,
 static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
 {
 	const unsigned char *data = *datap;
-	unsigned char cmd = *data++;
-	unsigned long size = cmd & ~0x80;
-	int i = 7;
-	while (cmd & 0x80) {
+	unsigned char cmd;
+	unsigned long size = 0;
+	int i = 0;
+	do {
 		cmd = *data++;
 		size |= (cmd & ~0x80) << i;
 		i += 7;
-	}
+	} while (cmd & 0x80);
 	*datap = data;
 	return size;
 }
diff --git a/rev-list.c b/rev-list.c
index a554e07396..63391fc113 100644
--- a/rev-list.c
+++ b/rev-list.c
@@ -32,6 +32,7 @@ static const char rev_list_usage[] =
 "    --objects\n"
 "    --unpacked\n"
 "    --header | --pretty\n"
+"    --abbrev=nr | --no-abbrev\n"
 "  special purpose:\n"
 "    --bisect"
 ;
@@ -43,6 +44,7 @@ static int tag_objects = 0;
 static int tree_objects = 0;
 static int blob_objects = 0;
 static int verbose_header = 0;
+static int abbrev = DEFAULT_ABBREV;
 static int show_parents = 0;
 static int hdr_termination = 0;
 static const char *commit_prefix = "";
@@ -96,7 +98,7 @@ static void show_commit(struct commit *commit)
 
 	if (verbose_header) {
 		static char pretty_header[16384];
-		pretty_print_commit(commit_format, commit, ~0, pretty_header, sizeof(pretty_header), 0);
+		pretty_print_commit(commit_format, commit, ~0, pretty_header, sizeof(pretty_header), abbrev);
 		printf("%s%c", pretty_header, hdr_termination);
 	}
 	fflush(stdout);
@@ -795,6 +797,18 @@ int main(int argc, const char **argv)
 			verbose_header = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--no-abbrev")) {
+			abbrev = 0;
+			continue;
+		}
+		if (!strncmp(arg, "--abbrev=", 9)) {
+			abbrev = strtoul(arg + 9, NULL, 10);
+			if (abbrev && abbrev < MINIMUM_ABBREV)
+				abbrev = MINIMUM_ABBREV;
+			else if (40 < abbrev)
+				abbrev = 40;
+			continue;
+		}
 		if (!strncmp(arg, "--pretty", 8)) {
 			commit_format = get_commit_format(arg+8);
 			verbose_header = 1;