diff --git a/src/lagrangian/distributionModels/RosinRammler/RosinRammler.C b/src/lagrangian/distributionModels/RosinRammler/RosinRammler.C
index 8cd242a961..13a41a138d 100644
--- a/src/lagrangian/distributionModels/RosinRammler/RosinRammler.C
+++ b/src/lagrangian/distributionModels/RosinRammler/RosinRammler.C
@@ -100,13 +100,13 @@ Foam::scalar Foam::distributionModels::RosinRammler::sample() const
 Foam::scalar Foam::distributionModels::RosinRammler::meanValue() const
 {
     // (C:Eq. 5)
-    const scalar a = scalar(1)/lambda_ + scalar(1);
-    const scalar qMax = pow(maxValue_/n_, lambda_);
-    const scalar qMin = pow(minValue_/n_, lambda_);
+    const scalar a = scalar(1)/n_ + scalar(1);
+    const scalar qMax = pow(maxValue_/lambda_, n_);
+    const scalar qMin = pow(minValue_/lambda_, n_);
     const scalar gMax = Math::incGamma_P(a, qMax);
     const scalar gMin = Math::incGamma_P(a, qMin);
 
-    return n_/(exp(-qMin) - exp(-qMax))*(gMax - gMin);
+    return lambda_/(exp(-qMin) - exp(-qMax))*(gMax - gMin);
 }