1 files changed, 1 insertions, 1 deletions
diff --git a/pack.c b/pack.c
index 5a603e0..e18455c 100644
--- a/pack.c
+++ b/pack.c
@@ -35,7 +35,7 @@ enum pack_status pack(void *buf_, size_t size, const char *fmt, ...)
 		size_t s;
 		union { uintmax_t unsigned_; intmax_t signed_; } v;
 		tr_debug("i: %d, fmt[i]: %c", i, fmt[i]);
-		sign = islower(fmt[i]);
+		sign = safe_islower(fmt[i]);
 		switch (fmt[i]) {
 		case '>': endianness = PACK_ENDIAN_BIG; continue;
 		case '<': endianness = PACK_ENDIAN_LITTLE; continue;