diff --git a/src/functional/snprintf.c b/src/functional/snprintf.c
index c96f151..70c1118 100644
--- a/src/functional/snprintf.c
+++ b/src/functional/snprintf.c
@@ -60,6 +60,20 @@ static const struct {
 	{ "%o", 15, "17" },
 	{ "%#o", 15, "017" },
 
+	/* octal: corner cases */
+	{ "%#o", 0, "0" },
+	{ "%#.0o", 0, "0" },
+	{ "%#.1o", 0, "0" },
+	{ "%#o", 1, "01" },
+	{ "%#.0o", 1, "01" },
+	{ "%#.1o", 1, "01" },
+	{ "%#04o", 1, "0001" },
+	{ "%#04.0o", 1, "  01" },
+	{ "%#04.1o", 1, "  01" },
+	{ "%04o", 1, "0001" },
+	{ "%04.0o", 1, "   1" },
+	{ "%04.1o", 1, "   1" },
+
 	{ NULL, 0.0, NULL }
 };