diff --git a/src/thermophysicalModels/specie/reaction/reactionRate/LangmuirHinshelwood/LangmuirHinshelwoodReactionRateI.H b/src/thermophysicalModels/specie/reaction/reactionRate/LangmuirHinshelwood/LangmuirHinshelwoodReactionRateI.H
index 9e462d3a4c..fd78b9e72b 100644
--- a/src/thermophysicalModels/specie/reaction/reactionRate/LangmuirHinshelwood/LangmuirHinshelwoodReactionRateI.H
+++ b/src/thermophysicalModels/specie/reaction/reactionRate/LangmuirHinshelwood/LangmuirHinshelwoodReactionRateI.H
@@ -35,8 +35,8 @@ inline Foam::LangmuirHinshelwoodReactionRate::LangmuirHinshelwoodReactionRate
 )
 :
     species_(st),
-    a_(st["A"]),
-    b_(st["B"])
+    a_(st[dict.lookup("A")]),
+    b_(st[dict.lookup("B")])
 {
     // Read (A, Ta) pairs
     FixedList<Tuple2<scalar, scalar>, n_> coeffs(dict.lookup("coeffs"));