diff --git a/src/mlpack/bindings/R/mlpack/src/r_util.cpp b/src/mlpack/bindings/R/mlpack/src/r_util.cpp
index e529fcdd75..b8be116ae8 100644
--- a/src/mlpack/bindings/R/mlpack/src/r_util.cpp
+++ b/src/mlpack/bindings/R/mlpack/src/r_util.cpp
@@ -35,7 +35,6 @@ bool inline inplace_transpose(arma::Mat<eT>& X)
 SEXP CreateParams(const std::string& bindingName)
 {
   util::Params* p = new util::Params(IO::Parameters(bindingName));
-  std::cout << "create params " << p << "\n";
   return std::move(Rcpp::XPtr<util::Params>(p));
 }
 
@@ -44,7 +43,6 @@ SEXP CreateParams(const std::string& bindingName)
 SEXP CreateTimers()
 {
   util::Timers* t = new util::Timers();
-  std::cout << "create timers " << t << "\n";
   return std::move(Rcpp::XPtr<util::Timers>(t));
 }
 
@@ -91,8 +89,8 @@ void SetParamBool(SEXP params, const std::string& paramName, bool paramValue)
 // Call params.Get<std::vector<std::string>>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamVecString(SEXP params,
-                          const std::string& paramName,
-                          const std::vector<std::string>& str)
+                       const std::string& paramName,
+                       const std::vector<std::string>& str)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   p.Get<std::vector<std::string>>(paramName) = std::move(str);
@@ -102,8 +100,8 @@ void SetParamVecString(SEXP params,
 // Call params.Get<std::vector<int>>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamVecInt(SEXP params,
-                       const std::string& paramName,
-                       const std::vector<int>& ints)
+                    const std::string& paramName,
+                    const std::vector<int>& ints)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   p.Get<std::vector<int>>(paramName) = std::move(ints);
@@ -113,8 +111,8 @@ void SetParamVecInt(SEXP params,
 // Call params.Get<arma::mat>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamMat(SEXP params,
-                    const std::string& paramName,
-                    const arma::mat& paramValue)
+                 const std::string& paramName,
+                 const arma::mat& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   p.Get<arma::mat>(paramName) = paramValue.t();
@@ -124,8 +122,8 @@ void SetParamMat(SEXP params,
 // Call params.Get<arma::Mat<size_t>>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamUMat(SEXP params,
-                     const std::string& paramName,
-                     const arma::Mat<size_t>& paramValue)
+                  const std::string& paramName,
+                  const arma::Mat<size_t>& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   p.Get<arma::Mat<size_t>>(paramName) = paramValue.t();
@@ -135,8 +133,8 @@ void SetParamUMat(SEXP params,
 // Call params.Get<arma::rowvec>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamRow(SEXP params,
-                    const std::string& paramName,
-                    const arma::rowvec& paramValue)
+                 const std::string& paramName,
+                 const arma::rowvec& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   p.Get<arma::rowvec>(paramName) = std::move(paramValue);
@@ -146,10 +144,19 @@ void SetParamRow(SEXP params,
 // Call params.Get<arma::Row<size_t>>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamURow(SEXP params,
-                     const std::string& paramName,
-                     const arma::Row<size_t>& paramValue)
+                  const std::string& paramName,
+                  const arma::Row<size_t>& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
+
+  // Check for zeros in the input---if we received these, the user is mistaken,
+  // because in R labels should start from 1.
+  if (arma::any(paramValue == 0))
+  {
+    Log::Fatal << "When passing labels from R to mlpack, labels should be in "
+        << "the range from 1 to the number of classes!" << std::endl;
+  }
+
   p.Get<arma::Row<size_t>>(paramName) = paramValue - 1;
   p.SetPassed(paramName);
 }
@@ -157,8 +164,8 @@ void SetParamURow(SEXP params,
 // Call params.Get<arma::vec>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamCol(SEXP params,
-                    const std::string& paramName,
-                    const arma::vec& paramValue)
+                 const std::string& paramName,
+                 const arma::vec& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   p.Get<arma::vec>(paramName) = std::move(paramValue);
@@ -168,10 +175,19 @@ void SetParamCol(SEXP params,
 // Call params.Get<arma::Col<size_t>>() to set the value of a parameter.
 // [[Rcpp::export]]
 void SetParamUCol(SEXP params,
-                     const std::string& paramName,
-                     const arma::Col<size_t>& paramValue)
+                  const std::string& paramName,
+                  const arma::Col<size_t>& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
+
+  // Check for zeros in the input---if we received these, the user is mistaken,
+  // because in R labels should start from 1.
+  if (arma::any(paramValue == 0))
+  {
+    Log::Fatal << "When passing labels from R to mlpack, labels should be in "
+        << "the range from 1 to the number of classes!" << std::endl;
+  }
+
   p.Get<arma::Col<size_t>>(paramName) = paramValue - 1;
   p.SetPassed(paramName);
 }
@@ -180,9 +196,9 @@ void SetParamUCol(SEXP params,
 // of a parameter.
 // [[Rcpp::export]]
 void SetParamMatWithInfo(SEXP params,
-                            const std::string& paramName,
-                            const LogicalVector& dimensions,
-                            const arma::mat& paramValue)
+                         const std::string& paramName,
+                         const LogicalVector& dimensions,
+                         const arma::mat& paramValue)
 {
   util::Params& p = *Rcpp::as<Rcpp::XPtr<util::Params>>(params);
   data::DatasetInfo d(paramValue.n_cols);
diff --git a/src/mlpack/bindings/R/mlpack/tests/testthat/test-R_binding.R b/src/mlpack/bindings/R/mlpack/tests/testthat/test-R_binding.R
index ee77ad3c33..789f3056be 100644
--- a/src/mlpack/bindings/R/mlpack/tests/testthat/test-R_binding.R
+++ b/src/mlpack/bindings/R/mlpack/tests/testthat/test-R_binding.R
@@ -126,7 +126,7 @@ test_that("TestCol", {
 
 # Test an unsigned column vector input parameter.
 test_that("TestUCol", {
-  x <- matrix(as.integer(rexp(100, rate = .1)), nrow = 1)
+  x <- matrix(as.integer(rexp(100, rate = .1)), nrow = 1) + 1
 
   output <- test_r_binding(4.0, 12, "hello",
                            ucol_in=x)
@@ -148,7 +148,7 @@ test_that("TestRow", {
 
 # Test an unsigned row vector input parameter.
 test_that("TestURow", {
-  x <- matrix(as.integer(rexp(100, rate = .1)), ncol = 1)
+  x <- matrix(as.integer(rexp(100, rate = .1)), ncol = 1) + 1
 
   output <- test_r_binding(4.0, 12, "hello",
                            urow_in=x)
@@ -269,6 +269,15 @@ test_that("TestNotMatrix", {
                               matrix_and_info_in=1e6))
 })
 
+# If we pass labels that start from 0, we should get an error.
+test_that("TestZeroLabels", {
+  x <- vector(mode="integer", 10)
+  expect_error(test_r_binding(4.0, 12, "hello", urow_in=x))
+
+  y <- matrix(0, 10, 1)
+  expect_error(test_r_binding(4.0, 12, "hello", ucol_in=y))
+})
+
 # First create a GaussianKernel object, then send it back and make sure we get
 # the right double value.
 test_that("TestModel", {