diff --git a/lib/filter.js b/lib/filter.js
index d2ec9e1..da9e10a 100644
--- a/lib/filter.js
+++ b/lib/filter.js
@@ -26,7 +26,7 @@ function logicHtml (str, data) {
   const exclude = options.exclude
   const globOptions = options.globOptions
 
-  let excludeString = exclude
+  let excludeString = exclude || ''
   if (Array.isArray(exclude)) excludeString = exclude.join('')
   if (excludeString.includes('/')) globOptions.basename = false
 
@@ -51,7 +51,7 @@ function logicCss (str, data) {
   const exclude = options.exclude
   const globOptions = options.globOptions
 
-  let excludeString = exclude
+  let excludeString = exclude || ''
   if (exclude && Array.isArray(exclude)) excludeString = exclude.join('')
   if (excludeString && excludeString.includes('/')) globOptions.basename = false
 
@@ -79,7 +79,7 @@ function logicJs (str, data) {
   const exclude = options.exclude
   const globOptions = options.globOptions
 
-  let excludeString = exclude
+  let excludeString = exclude || ''
   if (exclude && Array.isArray(exclude)) excludeString = exclude.join('')
   if (excludeString && excludeString.includes('/')) globOptions.basename = false
 
@@ -112,7 +112,7 @@ function logicSvg () {
   const include = options.include
   const globOptions = options.globOptions
 
-  let includeString = include
+  let includeString = include || ''
   if (include && Array.isArray(include)) includeString = include.join('')
   if (includeString && includeString.includes('/')) globOptions.basename = false
 
@@ -154,7 +154,7 @@ function logicGzip () {
   const include = options.include
   const globOptions = options.globOptions
 
-  let includeString = include
+  let includeString = include || ''
   if (include && Array.isArray(include)) includeString = include.join('')
   if (includeString && includeString.includes('/')) globOptions.basename = false
 
@@ -200,7 +200,7 @@ function logicBrotli () {
   const include = options.include
   const globOptions = options.globOptions
 
-  let includeString = include
+  let includeString = include || ''
   if (include && Array.isArray(include)) includeString = include.join('')
   if (includeString && includeString.includes('/')) globOptions.basename = false