diff --git a/src/rpn.rs b/src/rpn.rs
index 0168972..0cb23b8 100644
--- a/src/rpn.rs
+++ b/src/rpn.rs
@@ -165,7 +165,7 @@ fn eval(
 						Subtract => stack.push_back(y - x),
 						Multiply => stack.push_back(y * x),
 						Divide => stack.push_back(y / x),
-						Power => stack.push_back(x.powf(y)),
+						Power => stack.push_back(y.powf(x)),
 						Floor => stack.push_back((y / x).floor()),
 						Modulo => stack.push_back(y % x),
 						_ => {},