diff --git a/src/utils.rs b/src/utils.rs
index 105c488..91e1c56 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -10,8 +10,12 @@ pub enum PubkeyDecodeError {
 /// Accepts any checksum length >=3
 pub fn format_pubkey(raw: &str) -> Result<String, PubkeyDecodeError> {
 	let mut iter = raw.splitn(2, ':');
+	let raw_pubkey = iter.next().ok_or(PubkeyDecodeError::BadFormat)?;
+	if raw_pubkey.len() < 43 || raw_pubkey.len() > 44 {
+		return Err(PubkeyDecodeError::BadFormat);
+	}
 	let mut pubkey = [0u8; 32];
-	bs58::decode(iter.next().ok_or(PubkeyDecodeError::BadFormat)?)
+	bs58::decode(raw_pubkey)
 		.into(&mut pubkey)
 		.map_err(|_| PubkeyDecodeError::BadFormat)?;