diff --git a/R-package/DESCRIPTION b/R-package/DESCRIPTION
index 637e3435d..b1a91be17 100644
--- a/R-package/DESCRIPTION
+++ b/R-package/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: xgboost
 Type: Package
 Title: Extreme Gradient Boosting
-Version: 0.6.4.3
+Version: 0.6.4.4
 Date: 2017-01-04
 Author: Tianqi Chen <tianqi.tchen@gmail.com>, Tong He <hetong007@gmail.com>,
     Michael Benesty <michael@benesty.fr>, Vadim Khotilovich <khotilovich@gmail.com>,
diff --git a/R-package/NAMESPACE b/R-package/NAMESPACE
index c3fac04e3..031bc7880 100644
--- a/R-package/NAMESPACE
+++ b/R-package/NAMESPACE
@@ -76,4 +76,4 @@ importFrom(utils,head)
 importFrom(utils,object.size)
 importFrom(utils,str)
 importFrom(utils,tail)
-useDynLib(xgboost)
+useDynLib(xgboost, .registration = TRUE)
diff --git a/R-package/R/utils.R b/R-package/R/utils.R
index f66f7cf99..ce93b8235 100644
--- a/R-package/R/utils.R
+++ b/R-package/R/utils.R
@@ -130,12 +130,11 @@ xgb.iter.update <- function(booster_handle, dtrain, iter, obj = NULL) {
   }
 
   if (is.null(obj)) {
-    .Call("XGBoosterUpdateOneIter_R", booster_handle, as.integer(iter), dtrain,
-          PACKAGE = "xgboost")
+    .Call(XGBoosterUpdateOneIter_R, booster_handle, as.integer(iter), dtrain)
   } else {
     pred <- predict(booster_handle, dtrain)
     gpair <- obj(pred, dtrain)
-    .Call("XGBoosterBoostOneIter_R", booster_handle, dtrain, gpair$grad, gpair$hess, PACKAGE = "xgboost")
+    .Call(XGBoosterBoostOneIter_R, booster_handle, dtrain, gpair$grad, gpair$hess)
   }
   return(TRUE)
 }
@@ -153,8 +152,7 @@ xgb.iter.eval <- function(booster_handle, watchlist, iter, feval = NULL) {
   
   evnames <- names(watchlist)
   if (is.null(feval)) {
-    msg <- .Call("XGBoosterEvalOneIter_R", booster_handle, as.integer(iter), watchlist,
-                 as.list(evnames), PACKAGE = "xgboost")
+    msg <- .Call(XGBoosterEvalOneIter_R, booster_handle, as.integer(iter), watchlist, as.list(evnames))
     msg <- stri_split_regex(msg, '(\\s+|:|\\s+)')[[1]][-1]
     res <- as.numeric(msg[c(FALSE,TRUE)]) # even indices are the values
     names(res) <- msg[c(TRUE,FALSE)]      # odds are the names
diff --git a/R-package/R/xgb.Booster.R b/R-package/R/xgb.Booster.R
index 2b2d2f241..94bd27028 100644
--- a/R-package/R/xgb.Booster.R
+++ b/R-package/R/xgb.Booster.R
@@ -6,15 +6,15 @@ xgb.Booster.handle <- function(params = list(), cachelist = list(), modelfile =
     stop("cachelist must be a list of xgb.DMatrix objects")
   }
 
-  handle <- .Call("XGBoosterCreate_R", cachelist, PACKAGE = "xgboost")
+  handle <- .Call(XGBoosterCreate_R, cachelist)
   if (!is.null(modelfile)) {
     if (typeof(modelfile) == "character") {
-      .Call("XGBoosterLoadModel_R", handle, modelfile[1], PACKAGE = "xgboost")
+      .Call(XGBoosterLoadModel_R, handle, modelfile[1])
     } else if (typeof(modelfile) == "raw") {
-      .Call("XGBoosterLoadModelFromRaw_R", handle, modelfile, PACKAGE = "xgboost")
+      .Call(XGBoosterLoadModelFromRaw_R, handle, modelfile)
     } else if (inherits(modelfile, "xgb.Booster")) {
       bst <- xgb.Booster.complete(modelfile, saveraw = TRUE)
-      .Call("XGBoosterLoadModelFromRaw_R", handle, bst$raw, PACKAGE = "xgboost")
+      .Call(XGBoosterLoadModelFromRaw_R, handle, bst$raw)
     } else {
       stop("modelfile must be either character filename, or raw booster dump, or xgb.Booster object")
     }
@@ -40,7 +40,7 @@ is.null.handle <- function(handle) {
   if (!identical(class(handle), "xgb.Booster.handle"))
     stop("argument type must be xgb.Booster.handle")
   
-  if (is.null(handle) || .Call("XGCheckNullPtr_R", handle, PACKAGE = "xgboost"))
+  if (is.null(handle) || .Call(XGCheckNullPtr_R, handle))
     return(TRUE)
   return(FALSE)
 }
@@ -237,8 +237,7 @@ predict.xgb.Booster <- function(object, newdata, missing = NA,
   
   option <- 0L + 1L * as.logical(outputmargin) + 2L * as.logical(predleaf)
   
-  ret <- .Call("XGBoosterPredict_R", object$handle, newdata, option[1],
-               as.integer(ntreelimit), PACKAGE = "xgboost")
+  ret <- .Call(XGBoosterPredict_R, object$handle, newdata, option[1], as.integer(ntreelimit))
   
   if (length(ret) %% nrow(newdata) != 0)
     stop("prediction length ", length(ret)," is not multiple of nrows(newdata) ", nrow(newdata))
@@ -338,7 +337,7 @@ predict.xgb.Booster.handle <- function(object, ...) {
 xgb.attr <- function(object, name) {
   if (is.null(name) || nchar(as.character(name[1])) == 0) stop("invalid attribute name")
   handle <- xgb.get.handle(object)
-  .Call("XGBoosterGetAttr_R", handle, as.character(name[1]), PACKAGE = "xgboost")
+  .Call(XGBoosterGetAttr_R, handle, as.character(name[1]))
 }
 
 #' @rdname xgb.attr
@@ -355,7 +354,7 @@ xgb.attr <- function(object, name) {
       value <- as.character(value[1])
     }
   }
-  .Call("XGBoosterSetAttr_R", handle, as.character(name[1]), value, PACKAGE = "xgboost")
+  .Call(XGBoosterSetAttr_R, handle, as.character(name[1]), value)
   if (is(object, 'xgb.Booster') && !is.null(object$raw)) {
     object$raw <- xgb.save.raw(object$handle)
   }
@@ -366,10 +365,10 @@ xgb.attr <- function(object, name) {
 #' @export
 xgb.attributes <- function(object) {
   handle <- xgb.get.handle(object)
-  attr_names <- .Call("XGBoosterGetAttrNames_R", handle, PACKAGE = "xgboost")
+  attr_names <- .Call(XGBoosterGetAttrNames_R, handle)
   if (is.null(attr_names)) return(NULL)
   res <- lapply(attr_names, function(x) {
-    .Call("XGBoosterGetAttr_R", handle, x, PACKAGE = "xgboost")
+    .Call(XGBoosterGetAttr_R, handle, x)
   })
   names(res) <- attr_names
   res
@@ -394,7 +393,7 @@ xgb.attributes <- function(object) {
   })
   handle <- xgb.get.handle(object)
   for (i in seq_along(a)) {
-    .Call("XGBoosterSetAttr_R", handle, names(a[i]), a[[i]], PACKAGE = "xgboost")
+    .Call(XGBoosterSetAttr_R, handle, names(a[i]), a[[i]])
   }
   if (is(object, 'xgb.Booster') && !is.null(object$raw)) {
     object$raw <- xgb.save.raw(object$handle)
@@ -435,7 +434,7 @@ xgb.attributes <- function(object) {
   p <- lapply(p, function(x) as.character(x)[1])
   handle <- xgb.get.handle(object)
   for (i in seq_along(p)) {
-    .Call("XGBoosterSetParam_R", handle, names(p[i]), p[[i]], PACKAGE = "xgboost")
+    .Call(XGBoosterSetParam_R, handle, names(p[i]), p[[i]])
   }
   if (is(object, 'xgb.Booster') && !is.null(object$raw)) {
     object$raw <- xgb.save.raw(object$handle)
diff --git a/R-package/R/xgb.DMatrix.R b/R-package/R/xgb.DMatrix.R
index 72b973e0d..a6b04a6b6 100644
--- a/R-package/R/xgb.DMatrix.R
+++ b/R-package/R/xgb.DMatrix.R
@@ -26,15 +26,12 @@ xgb.DMatrix <- function(data, info = list(), missing = NA, silent = FALSE, ...)
     if (length(data) > 1)
       stop("'data' has class 'character' and length ", length(data),
            ".\n  'data' accepts either a numeric matrix or a single filename.")
-    handle <- .Call("XGDMatrixCreateFromFile_R", data, as.integer(silent),
-                    PACKAGE = "xgboost")
+    handle <- .Call(XGDMatrixCreateFromFile_R, data, as.integer(silent))
   } else if (is.matrix(data)) {
-    handle <- .Call("XGDMatrixCreateFromMat_R", data, missing,
-                    PACKAGE = "xgboost")
+    handle <- .Call(XGDMatrixCreateFromMat_R, data, missing)
     cnames <- colnames(data)
   } else if (inherits(data, "dgCMatrix")) {
-    handle <- .Call("XGDMatrixCreateFromCSC_R", data@p, data@i, data@x, nrow(data),
-                    PACKAGE = "xgboost")
+    handle <- .Call(XGDMatrixCreateFromCSC_R, data@p, data@i, data@x, nrow(data))
     cnames <- colnames(data)
   } else {
     stop("xgb.DMatrix does not support construction from ", typeof(data))
@@ -100,8 +97,7 @@ xgb.get.DMatrix <- function(data, label = NULL, missing = NA, weight = NULL) {
 #' 
 #' @export
 dim.xgb.DMatrix <- function(x) {
-  c(.Call("XGDMatrixNumRow_R", x, PACKAGE = "xgboost"),
-    .Call("XGDMatrixNumCol_R", x, PACKAGE = "xgboost"))
+  c(.Call(XGDMatrixNumRow_R, x), .Call(XGDMatrixNumCol_R, x))
 }
 
 
@@ -193,7 +189,7 @@ getinfo.xgb.DMatrix <- function(object, name, ...) {
          "    'label', 'weight', 'base_margin', 'nrow'")
   }
   if (name != "nrow"){
-    ret <- .Call("XGDMatrixGetInfo_R", object, name, PACKAGE = "xgboost")
+    ret <- .Call(XGDMatrixGetInfo_R, object, name)
   } else {
     ret <- nrow(object)
   }
@@ -240,29 +236,25 @@ setinfo.xgb.DMatrix <- function(object, name, info, ...) {
   if (name == "label") {
     if (length(info) != nrow(object))
       stop("The length of labels must equal to the number of rows in the input data")
-    .Call("XGDMatrixSetInfo_R", object, name, as.numeric(info),
-          PACKAGE = "xgboost")
+    .Call(XGDMatrixSetInfo_R, object, name, as.numeric(info))
     return(TRUE)
   }
   if (name == "weight") {
     if (length(info) != nrow(object))
       stop("The length of weights must equal to the number of rows in the input data")
-    .Call("XGDMatrixSetInfo_R", object, name, as.numeric(info),
-          PACKAGE = "xgboost")
+    .Call(XGDMatrixSetInfo_R, object, name, as.numeric(info))
     return(TRUE)
   }
   if (name == "base_margin") {
     # if (length(info)!=nrow(object))
     #   stop("The length of base margin must equal to the number of rows in the input data")
-    .Call("XGDMatrixSetInfo_R", object, name, as.numeric(info),
-          PACKAGE = "xgboost")
+    .Call(XGDMatrixSetInfo_R, object, name, as.numeric(info))
     return(TRUE)
   }
   if (name == "group") {
     if (sum(info) != nrow(object))
       stop("The sum of groups must equal to the number of rows in the input data")
-    .Call("XGDMatrixSetInfo_R", object, name, as.integer(info),
-          PACKAGE = "xgboost")
+    .Call(XGDMatrixSetInfo_R, object, name, as.integer(info))
     return(TRUE)
   }
   stop("setinfo: unknown info name ", name)
@@ -302,7 +294,7 @@ slice.xgb.DMatrix <- function(object, idxset, ...) {
   if (!inherits(object, "xgb.DMatrix")) {
     stop("object must be xgb.DMatrix")
   }
-  ret <- .Call("XGDMatrixSliceDMatrix_R", object, idxset, PACKAGE = "xgboost")
+  ret <- .Call(XGDMatrixSliceDMatrix_R, object, idxset)
 
   attr_list <- attributes(object)
   nr <- nrow(object)
diff --git a/R-package/R/xgb.DMatrix.save.R b/R-package/R/xgb.DMatrix.save.R
index 4ba8c498c..f25d31e5f 100644
--- a/R-package/R/xgb.DMatrix.save.R
+++ b/R-package/R/xgb.DMatrix.save.R
@@ -18,6 +18,6 @@ xgb.DMatrix.save <- function(dmatrix, fname) {
   if (!inherits(dmatrix, "xgb.DMatrix"))
     stop("dmatrix must be xgb.DMatrix")
   
-  .Call("XGDMatrixSaveBinary_R", dmatrix, fname[1], 0L, PACKAGE = "xgboost")
+  .Call(XGDMatrixSaveBinary_R, dmatrix, fname[1], 0L)
   return(TRUE)
 }
diff --git a/R-package/R/xgb.dump.R b/R-package/R/xgb.dump.R
index b9c857012..e57058330 100644
--- a/R-package/R/xgb.dump.R
+++ b/R-package/R/xgb.dump.R
@@ -51,8 +51,8 @@ xgb.dump <- function(model, fname = NULL, fmap = "", with_stats=FALSE,
     stop("fmap: argument must be a character string (when provided)")
   
   model <- xgb.Booster.complete(model)
-  model_dump <- .Call("XGBoosterDumpModel_R", model$handle, NVL(fmap, "")[1], as.integer(with_stats),
-                      as.character(dump_format), PACKAGE = "xgboost")
+  model_dump <- .Call(XGBoosterDumpModel_R, model$handle, NVL(fmap, "")[1], as.integer(with_stats),
+                      as.character(dump_format))
 
   if (is.null(fname)) 
     model_dump <- stri_replace_all_regex(model_dump, '\t', '')
diff --git a/R-package/R/xgb.save.R b/R-package/R/xgb.save.R
index 5d95ee664..426c70d14 100644
--- a/R-package/R/xgb.save.R
+++ b/R-package/R/xgb.save.R
@@ -37,6 +37,6 @@ xgb.save <- function(model, fname) {
          if (inherits(model, "xgb.DMatrix")) " Use xgb.DMatrix.save to save an xgb.DMatrix object." else "")
   }
   model <- xgb.Booster.complete(model, saveraw = FALSE)
-  .Call("XGBoosterSaveModel_R", model$handle, fname[1], PACKAGE = "xgboost")
+  .Call(XGBoosterSaveModel_R, model$handle, fname[1])
   return(TRUE)
 }
diff --git a/R-package/R/xgb.save.raw.R b/R-package/R/xgb.save.raw.R
index 1743b67d7..ae27d04f0 100644
--- a/R-package/R/xgb.save.raw.R
+++ b/R-package/R/xgb.save.raw.R
@@ -19,5 +19,5 @@
 #' @export
 xgb.save.raw <- function(model) {
   model <- xgb.get.handle(model)
-  .Call("XGBoosterModelToRaw_R", model, PACKAGE = "xgboost")
+  .Call(XGBoosterModelToRaw_R, model)
 }
diff --git a/R-package/R/xgboost.R b/R-package/R/xgboost.R
index 11a96c269..66c4c1bd2 100644
--- a/R-package/R/xgboost.R
+++ b/R-package/R/xgboost.R
@@ -105,5 +105,5 @@ NULL
 #' @importFrom graphics title
 #' 
 #' @import methods
-#' @useDynLib xgboost
+#' @useDynLib xgboost, .registration = TRUE
 NULL
diff --git a/R-package/src/Makevars.in b/R-package/src/Makevars.in
index 53cd65563..26aa5386c 100644
--- a/R-package/src/Makevars.in
+++ b/R-package/src/Makevars.in
@@ -13,6 +13,6 @@ XGB_RFLAGS = -DXGBOOST_STRICT_R_MODE=1 -DDMLC_LOG_BEFORE_THROW=0\
 PKG_CPPFLAGS=  -I$(PKGROOT)/include -I$(PKGROOT)/dmlc-core/include -I$(PKGROOT)/rabit/include -I$(PKGROOT) $(XGB_RFLAGS)
 PKG_CXXFLAGS= @OPENMP_CXXFLAGS@ $(SHLIB_PTHREAD_FLAGS)
 PKG_LIBS = @OPENMP_CXXFLAGS@ $(SHLIB_PTHREAD_FLAGS)
-OBJECTS= ./xgboost_R.o ./xgboost_custom.o ./xgboost_assert.o\
+OBJECTS= ./xgboost_R.o ./xgboost_custom.o ./xgboost_assert.o ./init.o\
          $(PKGROOT)/amalgamation/xgboost-all0.o $(PKGROOT)/amalgamation/dmlc-minimum0.o\
          $(PKGROOT)/rabit/src/engine_empty.o $(PKGROOT)/rabit/src/c_api.o
diff --git a/R-package/src/Makevars.win b/R-package/src/Makevars.win
index ee2eb8982..953b5dc23 100644
--- a/R-package/src/Makevars.win
+++ b/R-package/src/Makevars.win
@@ -25,7 +25,7 @@ XGB_RFLAGS = -DXGBOOST_STRICT_R_MODE=1 -DDMLC_LOG_BEFORE_THROW=0\
 PKG_CPPFLAGS=  -I$(PKGROOT)/include -I$(PKGROOT)/dmlc-core/include -I$(PKGROOT)/rabit/include -I$(PKGROOT) $(XGB_RFLAGS)
 PKG_CXXFLAGS= $(SHLIB_OPENMP_CFLAGS) $(SHLIB_PTHREAD_FLAGS)
 PKG_LIBS = $(SHLIB_OPENMP_CFLAGS) $(SHLIB_PTHREAD_FLAGS)
-OBJECTS= ./xgboost_R.o ./xgboost_custom.o ./xgboost_assert.o\
+OBJECTS= ./xgboost_R.o ./xgboost_custom.o ./xgboost_assert.o ./init.o\
          $(PKGROOT)/amalgamation/xgboost-all0.o $(PKGROOT)/amalgamation/dmlc-minimum0.o\
          $(PKGROOT)/rabit/src/engine_empty.o $(PKGROOT)/rabit/src/c_api.o
 
diff --git a/R-package/src/init.c b/R-package/src/init.c
new file mode 100644
index 000000000..c19e618b9
--- /dev/null
+++ b/R-package/src/init.c
@@ -0,0 +1,74 @@
+/* Copyright (c) 2015 by Contributors
+ * 
+ * This file was initially generated using the following R command:
+ * tools::package_native_routine_registration_skeleton('.', con = 'src/init.c', character_only = F)
+ * and edited to conform to xgboost C linter requirements. For details, see
+ * https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Registering-native-routines
+ */
+#include <R.h>
+#include <Rinternals.h>
+#include <stdlib.h>
+#include <R_ext/Rdynload.h>
+
+/* FIXME: 
+Check these declarations against the C/Fortran source code.
+*/
+
+/* .Call calls */
+extern SEXP XGBoosterBoostOneIter_R(SEXP, SEXP, SEXP, SEXP);
+extern SEXP XGBoosterCreate_R(SEXP);
+extern SEXP XGBoosterDumpModel_R(SEXP, SEXP, SEXP, SEXP);
+extern SEXP XGBoosterEvalOneIter_R(SEXP, SEXP, SEXP, SEXP);
+extern SEXP XGBoosterGetAttr_R(SEXP, SEXP);
+extern SEXP XGBoosterGetAttrNames_R(SEXP);
+extern SEXP XGBoosterLoadModel_R(SEXP, SEXP);
+extern SEXP XGBoosterLoadModelFromRaw_R(SEXP, SEXP);
+extern SEXP XGBoosterModelToRaw_R(SEXP);
+extern SEXP XGBoosterPredict_R(SEXP, SEXP, SEXP, SEXP);
+extern SEXP XGBoosterSaveModel_R(SEXP, SEXP);
+extern SEXP XGBoosterSetAttr_R(SEXP, SEXP, SEXP);
+extern SEXP XGBoosterSetParam_R(SEXP, SEXP, SEXP);
+extern SEXP XGBoosterUpdateOneIter_R(SEXP, SEXP, SEXP);
+extern SEXP XGCheckNullPtr_R(SEXP);
+extern SEXP XGDMatrixCreateFromCSC_R(SEXP, SEXP, SEXP, SEXP);
+extern SEXP XGDMatrixCreateFromFile_R(SEXP, SEXP);
+extern SEXP XGDMatrixCreateFromMat_R(SEXP, SEXP);
+extern SEXP XGDMatrixGetInfo_R(SEXP, SEXP);
+extern SEXP XGDMatrixNumCol_R(SEXP);
+extern SEXP XGDMatrixNumRow_R(SEXP);
+extern SEXP XGDMatrixSaveBinary_R(SEXP, SEXP, SEXP);
+extern SEXP XGDMatrixSetInfo_R(SEXP, SEXP, SEXP);
+extern SEXP XGDMatrixSliceDMatrix_R(SEXP, SEXP);
+
+static const R_CallMethodDef CallEntries[] = {
+  {"XGBoosterBoostOneIter_R",     (DL_FUNC) &XGBoosterBoostOneIter_R,     4},
+  {"XGBoosterCreate_R",           (DL_FUNC) &XGBoosterCreate_R,           1},
+  {"XGBoosterDumpModel_R",        (DL_FUNC) &XGBoosterDumpModel_R,        4},
+  {"XGBoosterEvalOneIter_R",      (DL_FUNC) &XGBoosterEvalOneIter_R,      4},
+  {"XGBoosterGetAttr_R",          (DL_FUNC) &XGBoosterGetAttr_R,          2},
+  {"XGBoosterGetAttrNames_R",     (DL_FUNC) &XGBoosterGetAttrNames_R,     1},
+  {"XGBoosterLoadModel_R",        (DL_FUNC) &XGBoosterLoadModel_R,        2},
+  {"XGBoosterLoadModelFromRaw_R", (DL_FUNC) &XGBoosterLoadModelFromRaw_R, 2},
+  {"XGBoosterModelToRaw_R",       (DL_FUNC) &XGBoosterModelToRaw_R,       1},
+  {"XGBoosterPredict_R",          (DL_FUNC) &XGBoosterPredict_R,          4},
+  {"XGBoosterSaveModel_R",        (DL_FUNC) &XGBoosterSaveModel_R,        2},
+  {"XGBoosterSetAttr_R",          (DL_FUNC) &XGBoosterSetAttr_R,          3},
+  {"XGBoosterSetParam_R",         (DL_FUNC) &XGBoosterSetParam_R,         3},
+  {"XGBoosterUpdateOneIter_R",    (DL_FUNC) &XGBoosterUpdateOneIter_R,    3},
+  {"XGCheckNullPtr_R",            (DL_FUNC) &XGCheckNullPtr_R,            1},
+  {"XGDMatrixCreateFromCSC_R",    (DL_FUNC) &XGDMatrixCreateFromCSC_R,    4},
+  {"XGDMatrixCreateFromFile_R",   (DL_FUNC) &XGDMatrixCreateFromFile_R,   2},
+  {"XGDMatrixCreateFromMat_R",    (DL_FUNC) &XGDMatrixCreateFromMat_R,    2},
+  {"XGDMatrixGetInfo_R",          (DL_FUNC) &XGDMatrixGetInfo_R,          2},
+  {"XGDMatrixNumCol_R",           (DL_FUNC) &XGDMatrixNumCol_R,           1},
+  {"XGDMatrixNumRow_R",           (DL_FUNC) &XGDMatrixNumRow_R,           1},
+  {"XGDMatrixSaveBinary_R",       (DL_FUNC) &XGDMatrixSaveBinary_R,       3},
+  {"XGDMatrixSetInfo_R",          (DL_FUNC) &XGDMatrixSetInfo_R,          3},
+  {"XGDMatrixSliceDMatrix_R",     (DL_FUNC) &XGDMatrixSliceDMatrix_R,     2},
+  {NULL, NULL, 0}
+};
+
+void R_init_xgboost(DllInfo *dll) {
+  R_registerRoutines(dll, NULL, CallEntries, NULL, NULL);
+  R_useDynamicSymbols(dll, FALSE);
+}
diff --git a/doc/how_to/contribute.md b/doc/how_to/contribute.md
index bad0455ad..5a5b58b8b 100644
--- a/doc/how_to/contribute.md
+++ b/doc/how_to/contribute.md
@@ -158,3 +158,7 @@ Some additional consideration is needed when the core library version changes.
 E.g., after the core changes from 0.6 to 0.7, the R package development version would become 0.7.0.1, working towards
 a 0.7.1 CRAN release. The 0.7.0 would not be released to CRAN, unless it would require almost no additional development.
 
+### Registering native routines in R
+According to [R extension manual](https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Registering-native-routines),
+it is good practice to register native routines and to disable symbol search. When any changes or additions are made to the
+C++ interface of the R package, please make corresponding changes in ```src/init.c``` as well.
diff --git a/include/xgboost/c_api.h b/include/xgboost/c_api.h
index f4792ad5a..decdcd0bf 100644
--- a/include/xgboost/c_api.h
+++ b/include/xgboost/c_api.h
@@ -2,11 +2,13 @@
  * Copyright (c) 2015 by Contributors
  * \file c_api.h
  * \author Tianqi Chen
- * \brief C API of XGBoost, used to interfacing with other languages.
+ * \brief C API of XGBoost, used for interfacing to other languages.
  */
 #ifndef XGBOOST_C_API_H_
 #define XGBOOST_C_API_H_
 
+#include <cstdint>
+
 #ifdef __cplusplus
 #define XGB_EXTERN_C extern "C"
 #endif
@@ -62,7 +64,7 @@ typedef struct {
 /*!
  * \brief Callback to set the data to handle,
  * \param handle The handle to the callback.
- * \param batch The data content to be setted.
+ * \param batch The data content to be set.
  */
 XGB_EXTERN_C typedef int XGBCallbackSetData(
     DataHolderHandle handle, XGBoostBatchCSR batch);