diff --git a/src/stan/analyze/mcmc/split_chains.hpp b/src/stan/analyze/mcmc/split_chains.hpp
index 9a7fb9aac1..fa89f6dc29 100644
--- a/src/stan/analyze/mcmc/split_chains.hpp
+++ b/src/stan/analyze/mcmc/split_chains.hpp
@@ -56,8 +56,8 @@ inline Eigen::MatrixXd split_chains(const Eigen::MatrixXd& samples) {
   int split_i = 0;
   for (std::size_t i = 0; i < num_chains; ++i) {
     Eigen::Map<const Eigen::VectorXd> head_block(samples.col(i).data(), half);
-    Eigen::Map<const Eigen::VectorXd> tail_block(samples.col(i).data() + tail_start,
-                                                 half);
+    Eigen::Map<const Eigen::VectorXd> tail_block(
+        samples.col(i).data() + tail_start, half);
 
     split_draws_matrix.col(split_i) = head_block;
     split_draws_matrix.col(split_i + 1) = tail_block;
diff --git a/src/test/unit/analyze/mcmc/split_chains_test.cpp b/src/test/unit/analyze/mcmc/split_chains_test.cpp
index 0725ef6d5c..a027937da7 100644
--- a/src/test/unit/analyze/mcmc/split_chains_test.cpp
+++ b/src/test/unit/analyze/mcmc/split_chains_test.cpp
@@ -123,18 +123,18 @@ TEST_F(SplitChains, split_draws_matrix_odd_rows) {
   auto bar = stan::analyze::split_chains(foo);
   EXPECT_EQ(4, bar.cols());
   EXPECT_EQ(3, bar.rows());
-  EXPECT_EQ(bar(0,0), 1);
-  EXPECT_EQ(bar(1,0), 2);
-  EXPECT_EQ(bar(2,0), 3);
-  EXPECT_EQ(bar(0,1), 5);
-  EXPECT_EQ(bar(1,1), 6);
-  EXPECT_EQ(bar(2,1), 7);
-  EXPECT_EQ(bar(0,2), 8);
-  EXPECT_EQ(bar(1,2), 9);
-  EXPECT_EQ(bar(2,2), 10);
-  EXPECT_EQ(bar(0,3), 12);
-  EXPECT_EQ(bar(1,3), 13);
-  EXPECT_EQ(bar(2,3), 14);
+  EXPECT_EQ(bar(0, 0), 1);
+  EXPECT_EQ(bar(1, 0), 2);
+  EXPECT_EQ(bar(2, 0), 3);
+  EXPECT_EQ(bar(0, 1), 5);
+  EXPECT_EQ(bar(1, 1), 6);
+  EXPECT_EQ(bar(2, 1), 7);
+  EXPECT_EQ(bar(0, 2), 8);
+  EXPECT_EQ(bar(1, 2), 9);
+  EXPECT_EQ(bar(2, 2), 10);
+  EXPECT_EQ(bar(0, 3), 12);
+  EXPECT_EQ(bar(1, 3), 13);
+  EXPECT_EQ(bar(2, 3), 14);
 
   Eigen::MatrixXd baz(4, 2);
   for (size_t col = 0; col < 2; ++col) {
@@ -146,12 +146,12 @@ TEST_F(SplitChains, split_draws_matrix_odd_rows) {
   auto boz = stan::analyze::split_chains(baz);
   EXPECT_EQ(4, boz.cols());
   EXPECT_EQ(2, boz.rows());
-  EXPECT_EQ(boz(0,0), 15);
-  EXPECT_EQ(boz(1,0), 16);
-  EXPECT_EQ(boz(0,1), 17);
-  EXPECT_EQ(boz(1,1), 18);
-  EXPECT_EQ(boz(0,2), 19);
-  EXPECT_EQ(boz(1,2), 20);
-  EXPECT_EQ(boz(0,3), 21);
-  EXPECT_EQ(boz(1,3), 22);
+  EXPECT_EQ(boz(0, 0), 15);
+  EXPECT_EQ(boz(1, 0), 16);
+  EXPECT_EQ(boz(0, 1), 17);
+  EXPECT_EQ(boz(1, 1), 18);
+  EXPECT_EQ(boz(0, 2), 19);
+  EXPECT_EQ(boz(1, 2), 20);
+  EXPECT_EQ(boz(0, 3), 21);
+  EXPECT_EQ(boz(1, 3), 22);
 }