diff --git a/src/encode.rs b/src/encode.rs
index fe59294..fbbd3a5 100644
--- a/src/encode.rs
+++ b/src/encode.rs
@@ -80,9 +80,12 @@ impl<R: Read, W: Write> Encoder<R, W> {
                     num |= *n as u64;
                 }
             }
-            let pad = n_bytes * 8 % 6;
+            let mut outlen = n_bytes * 8 / 6;
+            if n_bytes * 8 % 6 > 0 {
+                outlen += 1;
+            }
             for idx in (0..4).rev() {
-                if pad == 0 || idx < 4 - pad {
+                if outlen == 4 || idx < outlen {
                     let b = num & 0b111111;
                     obuf[idx] = self.alphabet.items[b as usize];
                 }
@@ -96,7 +99,7 @@ impl<R: Read, W: Write> Encoder<R, W> {
                 char::try_from(obuf[2]).unwrap(),
                 char::try_from(obuf[3]).unwrap()
             )?;
-            if pad > 0 {
+            if outlen < 4 {
                 break;
             }
         }