diff --git a/imgui-examples/examples/test_window_impl.rs b/imgui-examples/examples/test_window_impl.rs
index 92f723c..dd13a71 100644
--- a/imgui-examples/examples/test_window_impl.rs
+++ b/imgui-examples/examples/test_window_impl.rs
@@ -752,7 +752,7 @@ CTRL+click on individual component to input value.\n",
             }
 
             for i in lines.iter() {
-                if state.filter.pass_filter(String::from(*i)) {
+                if state.filter.pass_filter(i) {
                     ui.bullet_text(i);
                 }
             }
diff --git a/imgui/src/widget/text_filter.rs b/imgui/src/widget/text_filter.rs
index eeac137..b64ebf9 100644
--- a/imgui/src/widget/text_filter.rs
+++ b/imgui/src/widget/text_filter.rs
@@ -63,7 +63,8 @@ impl TextFilter {
     /// Returns true if the buffer matches the filter.
     ///
     /// [`draw()`](Self::draw) or [`build()`](Self::build) mut be called **before** this function.
-    pub fn pass_filter(&self, mut buf: String) -> bool {
+    pub fn pass_filter(&self, buf: &str) -> bool {
+        let mut buf = String::from(buf);
         buf.push('\0');
         let ptr = buf.as_mut_ptr();
         unsafe {
@@ -71,7 +72,8 @@ impl TextFilter {
         }
     }
 
-    pub fn pass_filter_with_end(&self, mut start: String, mut end: String) -> bool {
+    pub fn pass_filter_with_end(&self, start: &str, end: &str) -> bool {
+        let (mut start, mut end) = (String::from(start), String::from(end));
         start.push('\0');
         end.push('\0');
         let b_ptr = start.as_mut_ptr();