diff --git a/cli.c b/cli.c
index 4139bc3..c758859 100644
--- a/cli.c
+++ b/cli.c
@@ -26,8 +26,6 @@
 #include "strtonum.h"
 #include "otp.h"
 
-#define LINE_SIZE 16384
-
 extern const char *__progname;
 
 static void
@@ -44,8 +42,9 @@ int
 main(int argc, char *argv[])
 {
 	const char *errstr;
-	char *key;
-	size_t key_len;
+	char *key, *line;
+	size_t key_len, linesz;
+	ssize_t linelen;
 	uint64_t counter;
 	unsigned int step;
 	int32_t r;
@@ -110,16 +109,17 @@ main(int argc, char *argv[])
 		key = argv[0];
 		key_len = strlen(key);
 	} else {
-		key = malloc(sizeof(uint8_t) * (LINE_SIZE + 1));
-		if (key == NULL)
-			err(1, "malloc");
-		if (fgets(key, LINE_SIZE + 1, stdin) == NULL)
-			err(1, "fgets");
-		key_len = strlen(key);
-		if (key[key_len - 1] == '\n') {
-			key[key_len - 1] = '\0';
-			key_len--;
+		line = NULL;
+		linesz = 0;
+		linelen = getline(&line, &linesz, stdin);
+		if (linelen == -1 && ferror(stdin))
+			err(1, "getline");
+		if (linelen > 0 && line[linelen - 1] == '\n') {
+			line[linelen - 1] = '\0';
+			linelen--;
 		}
+		key = line;
+		key_len = linelen;
 	}
 
 	if (do_hotp) {