diff --git a/src/frame/base.rs b/src/frame/base.rs
index 2bfddb5..5b485a4 100644
--- a/src/frame/base.rs
+++ b/src/frame/base.rs
@@ -473,7 +473,7 @@ impl<T: Clone + PartialEq> Frame<T> {
 
 
     /// Returns a new `Matrix` that is the transpose of the current frame's matrix.
-    pub fn transpose(&mut self) -> Matrix<T> {
+    pub fn transpose(&self) -> Matrix<T> {
         self.matrix.transpose()
     }