diff --git a/src/WABinary/encode.ts b/src/WABinary/encode.ts
index f1168a6..39f7881 100644
--- a/src/WABinary/encode.ts
+++ b/src/WABinary/encode.ts
@@ -149,8 +149,8 @@ const encodeBinaryNodeInner = (
 		}
 	}
 
-	const isNibble = (str: string) => {
-		if(str.length > TAGS.PACKED_MAX) {
+	const isNibble = (str?: string) => {
+		if(!str || str.length > TAGS.PACKED_MAX) {
 			return false
 		}
 
@@ -164,8 +164,8 @@ const encodeBinaryNodeInner = (
 		return true
 	}
 
-	const isHex = (str: string) => {
-		if(str.length > TAGS.PACKED_MAX) {
+	const isHex = (str?: string) => {
+		if(!str || str.length > TAGS.PACKED_MAX) {
 			return false
 		}
 
@@ -179,7 +179,12 @@ const encodeBinaryNodeInner = (
 		return true
 	}
 
-	const writeString = (str: string) => {
+	const writeString = (str?: string) => {
+		if(str === undefined || str === null) {
+			pushByte(TAGS.LIST_EMPTY)
+			return
+		}
+
 		const tokenIndex = TOKEN_MAP[str]
 		if(tokenIndex) {
 			if(typeof tokenIndex.dict === 'number') {
@@ -212,7 +217,11 @@ const encodeBinaryNodeInner = (
 		}
 	}
 
-	const validAttributes = Object.keys(attrs).filter(k => (
+	if(!tag) {
+		throw new Error('Invalid node: tag cannot be undefined')
+	}
+
+	const validAttributes = Object.keys(attrs || {}).filter(k => (
 		typeof attrs[k] !== 'undefined' && attrs[k] !== null
 	))
 
@@ -232,8 +241,10 @@ const encodeBinaryNodeInner = (
 		writeByteLength(content.length)
 		pushBytes(content)
 	} else if(Array.isArray(content)) {
-		writeListStart(content.length)
-		for(const item of content) {
+		const validContent = content.filter(item => item && (item.tag || Buffer.isBuffer(item) || item instanceof Uint8Array || typeof item === 'string')
+		)
+		writeListStart(validContent.length)
+		for(const item of validContent) {
 			encodeBinaryNodeInner(item, opts, buffer)
 		}
 	} else if(typeof content === 'undefined') {