1 files changed, 3 insertions, 3 deletions
diff --git a/src/lib.rs b/src/lib.rs
index cfa4ab2..de0db50 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -184,10 +184,10 @@ fn sigma_sub(p: &str, q: &str) -> f32 {
 ///
 /// (Kondrak 2002: 54)
 fn sigma_exp(p: &str, q: &str) -> f32 {
-    let q1 = q.chars().nth(0).unwrap().to_string();
-    let q2 = q.chars().nth(1).unwrap().to_string();
+    let q1 = &q[0..0];
+    let q2 = &q[1..1];
 
-    return EXTRACTED.cexp - delta(p, &q1) - delta(p, &q2) - V(p) - f32::max(V(&q1), V(&q2));
+    return EXTRACTED.cexp - delta(p, q1) - delta(p, q2) - V(p) - f32::max(V(&q1), V(&q2));
 }
 
 /// Return weighted sum of difference between P and Q.