diff --git a/builtin/blame.c b/builtin/blame.c
index cbb7dc2ad9..1fccbe6bff 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2609,6 +2609,8 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 	if (0 < abbrev && abbrev < GIT_SHA1_HEXSZ)
 		/* one more abbrev length is needed for the boundary commit */
 		abbrev++;
+	else if (!abbrev)
+		abbrev = GIT_SHA1_HEXSZ;
 
 	if (revs_file && read_ancestry(revs_file))
 		die_errno("reading graft file '%s' failed", revs_file);
diff --git a/t/t8002-blame.sh b/t/t8002-blame.sh
index c6347ad8fd..380e1c1054 100755
--- a/t/t8002-blame.sh
+++ b/t/t8002-blame.sh
@@ -114,4 +114,8 @@ test_expect_success 'blame --abbrev=40 behaves like -l' '
 	check_abbrev 39 --abbrev=40 ^HEAD
 '
 
+test_expect_success '--no-abbrev works like --abbrev=40' '
+	check_abbrev 40 --no-abbrev
+'
+
 test_done