diff --git a/ref-filter.c b/ref-filter.c
index 88b021dd1d0e30..fae9f4b8ed50b1 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -583,9 +583,10 @@ static int contents_atom_parser(struct ref_format *format, struct used_atom *ato
 		atom->u.contents.option = C_BARE;
 	else if (!strcmp(arg, "body"))
 		atom->u.contents.option = C_BODY;
-	else if (!strcmp(arg, "size"))
+	else if (!strcmp(arg, "size")) {
+		atom->type = FIELD_ULONG;
 		atom->u.contents.option = C_LENGTH;
-	else if (!strcmp(arg, "signature"))
+	} else if (!strcmp(arg, "signature"))
 		atom->u.contents.option = C_SIG;
 	else if (!strcmp(arg, "subject"))
 		atom->u.contents.option = C_SUB;
@@ -691,9 +692,10 @@ static int raw_atom_parser(struct ref_format *format UNUSED,
 {
 	if (!arg)
 		atom->u.raw_data.option = RAW_BARE;
-	else if (!strcmp(arg, "size"))
+	else if (!strcmp(arg, "size")) {
+		atom->type = FIELD_ULONG;
 		atom->u.raw_data.option = RAW_LENGTH;
-	else
+	} else
 		return err_bad_arg(err, "raw", arg);
 	return 0;
 }
@@ -1859,7 +1861,8 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, struct exp
 				v->s = xmemdupz(buf, buf_size);
 				v->s_size = buf_size;
 			} else if (atom->u.raw_data.option == RAW_LENGTH) {
-				v->s = xstrfmt("%"PRIuMAX, (uintmax_t)buf_size);
+				v->value = buf_size;
+				v->s = xstrfmt("%"PRIuMAX, v->value);
 			}
 			continue;
 		}
@@ -1885,9 +1888,10 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, struct exp
 			v->s = strbuf_detach(&sb, NULL);
 		} else if (atom->u.contents.option == C_BODY_DEP)
 			v->s = xmemdupz(bodypos, bodylen);
-		else if (atom->u.contents.option == C_LENGTH)
-			v->s = xstrfmt("%"PRIuMAX, (uintmax_t)strlen(subpos));
-		else if (atom->u.contents.option == C_BODY)
+		else if (atom->u.contents.option == C_LENGTH) {
+			v->value = strlen(subpos);
+			v->s = xstrfmt("%"PRIuMAX, v->value);
+		} else if (atom->u.contents.option == C_BODY)
 			v->s = xmemdupz(bodypos, nonsiglen);
 		else if (atom->u.contents.option == C_SIG)
 			v->s = xmemdupz(sigpos, siglen);
@@ -2267,6 +2271,7 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 
 		v->s_size = ATOM_SIZE_UNSPECIFIED;
 		v->handler = append_atom;
+		v->value = 0;
 		v->atom = atom;
 
 		if (*name == '*') {
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index aa3c7c03c40826..7b943fd34cdece 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -1017,16 +1017,16 @@ test_expect_success 'Verify sorts with raw' '
 test_expect_success 'Verify sorts with raw:size' '
 	cat >expected <<-EOF &&
 	refs/myblobs/blob8
-	refs/myblobs/first
 	refs/myblobs/blob7
-	refs/heads/main
 	refs/myblobs/blob4
 	refs/myblobs/blob1
 	refs/myblobs/blob2
 	refs/myblobs/blob3
 	refs/myblobs/blob5
 	refs/myblobs/blob6
+	refs/myblobs/first
 	refs/mytrees/first
+	refs/heads/main
 	EOF
 	git for-each-ref --format="%(refname)" --sort=raw:size \
 		refs/heads/main refs/myblobs/ refs/mytrees/first >actual &&
@@ -1138,6 +1138,17 @@ test_expect_success 'for-each-ref --format compare with cat-file --batch' '
 	test_cmp expected actual
 '
 
+test_expect_success 'verify sorts with contents:size' '
+	cat >expect <<-\EOF &&
+	refs/heads/main
+	refs/heads/newtag
+	refs/heads/ambiguous
+	EOF
+	git for-each-ref --format="%(refname)" \
+		--sort=contents:size refs/heads/ >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'set up multiple-sort tags' '
 	for when in 100000 200000
 	do