diff --git a/src/mlpack/methods/approx_kfn/approx_kfn_main.cpp b/src/mlpack/methods/approx_kfn/approx_kfn_main.cpp
index 42d07a0b31..f362ae7c00 100644
--- a/src/mlpack/methods/approx_kfn/approx_kfn_main.cpp
+++ b/src/mlpack/methods/approx_kfn/approx_kfn_main.cpp
@@ -266,8 +266,8 @@ static void mlpackMain()
         // Check the exact distances matrix has the right dimensions.
         RequireParamValue<arma::mat>("exact_distances",
           [&](const arma::mat& exactDists){ return (exactDists.n_rows == k); },
-          true, "the number of rows in exact distances matrix must be equal to
-          k.");
+          true, "the number of rows in exact distances matrix must be equal to "
+          "k.");
         RequireParamValue<arma::mat>("exact_distances",
           [&](const arma::mat& exactDists){ return (exactDists.n_cols ==
           referenceSet.n_cols); }, true, "the number of columns in exact "