diff --git a/pretty.c b/pretty.c
index a1a01492c19b6f..692a6382a11867 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1514,7 +1514,7 @@ static size_t format_and_pad_commit(struct strbuf *sb, /* in UTF-8 */
 			if (*ch != 'm')
 				break;
 			p = ch - 1;
-			while (ch - p < 10 && *p != '\033')
+			while (p > sb->buf && ch - p < 10 && *p != '\033')
 				p--;
 			if (*p != '\033' ||
 			    ch + 1 - p != display_mode_esc_sequence_len(p))
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index fff3e05615e42c..126dc20f23c9dd 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -867,6 +867,12 @@ test_expect_success 'log --pretty=reference is colored appropriately' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log --pretty with space stealing' '
+	printf mm0 >expect &&
+	git log -1 --pretty="format:mm%>>|(1)%x30" >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'log --pretty with huge commit message' '
 	# We only assert that this command does not crash. This needs to be
 	# executed with the address sanitizer to demonstrate failure.