2 files changed, 4 insertions, 2 deletions
diff --git a/src/util.c b/src/util.c
index 715ce4e..f6150f2 100644
--- a/src/util.c
+++ b/src/util.c
@@ -234,8 +234,8 @@ int
 xenopen(int status, const char *path, int flags, int mode, ...)
 {
 	int fd;
-	if (!strncmp(path, "/dev/fd/", sizeof("/dev/fd/") - 1)) {
-		if (!toi(path + sizeof("/dev/fd/") - 1, 0, INT_MAX, &fd))
+	if (!strncmp(path, "/dev/fd/", STRLEN("/dev/fd/"))) {
+		if (!toi(path + STRLEN("/dev/fd/"), 0, INT_MAX, &fd))
 			return fd;
 	} else if (!strcmp(path, "/dev/stdin")) {
 		return STDIN_FILENO;
diff --git a/src/util.h b/src/util.h
index 42b5df5..ce5f647 100644
--- a/src/util.h
+++ b/src/util.h
@@ -5,6 +5,8 @@
 #define MIN(A, B)         ((A) < (B) ? (A) : (B))
 #define MAX(A, B)         ((A) > (B) ? (A) : (B))
 #define CLIP(A, B, C)     ((B) < (A) ? (A) : (B) > (C) ? (C) : (B))
+#define STRLEN(STR)       (sizeof(STR) - 1)
+#define INTSTRLEN(TYPE)   ((sizeof(TYPE) == 1 ? 3 : (5 * sizeof(TYPE) / 2)) + (TYPE)-1 < 0)
 
 #define USAGE(SYNOPSIS)\
 	static void usage(void)\