diff --git a/builtin/log.c b/builtin/log.c
index e6cab12018..b8cdf2b9d9 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1042,7 +1042,6 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 	diff_flush(&opts);
 
 	fprintf(rev->diffopt.file, "\n");
-	print_signature(rev->diffopt.file);
 }
 
 static const char *clean_message_id(const char *msg_id)
@@ -1361,7 +1360,7 @@ static void print_bases(struct base_tree_info *bases, FILE *file)
 		return;
 
 	/* Show the base commit */
-	fprintf(file, "base-commit: %s\n", oid_to_hex(&bases->base_commit));
+	fprintf(file, "\nbase-commit: %s\n", oid_to_hex(&bases->base_commit));
 
 	/* Show the prerequisite patches */
 	for (i = bases->nr_patch_id - 1; i >= 0; i--)
@@ -1720,6 +1719,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		make_cover_letter(&rev, use_stdout,
 				  origin, nr, list, branch_name, quiet);
 		print_bases(&bases, rev.diffopt.file);
+		print_signature(rev.diffopt.file);
 		total++;
 		start_number--;
 	}
@@ -1779,13 +1779,13 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		if (!use_stdout)
 			rev.shown_one = 0;
 		if (shown) {
+			print_bases(&bases, rev.diffopt.file);
 			if (rev.mime_boundary)
 				fprintf(rev.diffopt.file, "\n--%s%s--\n\n\n",
 				       mime_boundary_leader,
 				       rev.mime_boundary);
 			else
 				print_signature(rev.diffopt.file);
-			print_bases(&bases, rev.diffopt.file);
 		}
 		if (!use_stdout)
 			fclose(rev.diffopt.file);
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index b0579dd452..8d90a6e500 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -754,9 +754,22 @@ test_expect_success 'format-patch --ignore-if-in-upstream HEAD' '
 	git format-patch --ignore-if-in-upstream HEAD
 '
 
+git_version="$(git --version | sed "s/.* //")"
+
+signature() {
+	printf "%s\n%s\n\n" "-- " "${1:-$git_version}"
+}
+
+test_expect_success 'format-patch default signature' '
+	git format-patch --stdout -1 | tail -n 3 >output &&
+	signature >expect &&
+	test_cmp expect output
+'
+
 test_expect_success 'format-patch --signature' '
-	git format-patch --stdout --signature="my sig" -1 >output &&
-	grep "my sig" output
+	git format-patch --stdout --signature="my sig" -1 | tail -n 3 >output &&
+	signature "my sig" >expect &&
+	test_cmp expect output
 '
 
 test_expect_success 'format-patch with format.signature config' '
@@ -1502,12 +1515,12 @@ test_expect_success 'format-patch -o overrides format.outputDirectory' '
 
 test_expect_success 'format-patch --base' '
 	git checkout side &&
-	git format-patch --stdout --base=HEAD~3 -1 >patch &&
-	grep "^base-commit:" patch >actual &&
-	grep "^prerequisite-patch-id:" patch >>actual &&
-	echo "base-commit: $(git rev-parse HEAD~3)" >expected &&
+	git format-patch --stdout --base=HEAD~3 -1 | tail -n 7 >actual &&
+	echo >expected &&
+	echo "base-commit: $(git rev-parse HEAD~3)" >>expected &&
 	echo "prerequisite-patch-id: $(git show --patch HEAD~2 | git patch-id --stable | awk "{print \$1}")" >>expected &&
 	echo "prerequisite-patch-id: $(git show --patch HEAD~1 | git patch-id --stable | awk "{print \$1}")" >>expected &&
+	signature >> expected &&
 	test_cmp expected actual
 '
 
@@ -1605,6 +1618,14 @@ test_expect_success 'format-patch --base overrides format.useAutoBase' '
 	test_cmp expected actual
 '
 
+test_expect_success 'format-patch --base with --attach' '
+	git format-patch --attach=mimemime --stdout --base=HEAD~ -1 >patch &&
+	sed -n -e "/^base-commit:/s/.*/1/p" -e "/^---*mimemime--$/s/.*/2/p" \
+		patch >actual &&
+	test_write_lines 1 2 >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'format-patch --pretty=mboxrd' '
 	sp=" " &&
 	cat >msg <<-INPUT_END &&