diff --git a/R-package/CMakeLists.txt b/R-package/CMakeLists.txt
index 003a635a5485..a19e56f4e6eb 100644
--- a/R-package/CMakeLists.txt
+++ b/R-package/CMakeLists.txt
@@ -1,41 +1,54 @@
 find_package(LibR REQUIRED)
 message(STATUS "LIBR_CORE_LIBRARY " ${LIBR_CORE_LIBRARY})
 
-file(GLOB_RECURSE R_SOURCES
+file(
+  GLOB_RECURSE R_SOURCES
   ${CMAKE_CURRENT_LIST_DIR}/src/*.cc
-  ${CMAKE_CURRENT_LIST_DIR}/src/*.c)
+  ${CMAKE_CURRENT_LIST_DIR}/src/*.c
+)
+
 # Use object library to expose symbols
 add_library(xgboost-r OBJECT ${R_SOURCES})
-if (ENABLE_ALL_WARNINGS)
+
+if(ENABLE_ALL_WARNINGS)
   target_compile_options(xgboost-r PRIVATE -Wall -Wextra)
-endif (ENABLE_ALL_WARNINGS)
-target_compile_definitions(xgboost-r
-  PUBLIC
+endif()
+
+target_compile_definitions(
+  xgboost-r PUBLIC
   -DXGBOOST_STRICT_R_MODE=1
   -DXGBOOST_CUSTOMIZE_GLOBAL_PRNG=1
   -DDMLC_LOG_BEFORE_THROW=0
   -DDMLC_DISABLE_STDIN=1
   -DDMLC_LOG_CUSTOMIZE=1
-  -DRABIT_STRICT_CXX98_)
-target_include_directories(xgboost-r
-  PRIVATE
+  -DRABIT_STRICT_CXX98_
+)
+
+target_include_directories(
+  xgboost-r PRIVATE
   ${LIBR_INCLUDE_DIRS}
   ${PROJECT_SOURCE_DIR}/include
   ${PROJECT_SOURCE_DIR}/dmlc-core/include
-  ${PROJECT_SOURCE_DIR}/rabit/include)
+  ${PROJECT_SOURCE_DIR}/rabit/include
+)
+
 target_link_libraries(xgboost-r PUBLIC ${LIBR_CORE_LIBRARY})
-if (USE_OPENMP)
+
+if(USE_OPENMP)
   find_package(OpenMP REQUIRED)
   target_link_libraries(xgboost-r PUBLIC OpenMP::OpenMP_CXX OpenMP::OpenMP_C)
-endif (USE_OPENMP)
+endif()
+
 set_target_properties(
   xgboost-r PROPERTIES
   CXX_STANDARD 17
   CXX_STANDARD_REQUIRED ON
-  POSITION_INDEPENDENT_CODE ON)
+  POSITION_INDEPENDENT_CODE ON
+)
 
 # Get compilation and link flags of xgboost-r and propagate to objxgboost
 target_link_libraries(objxgboost PUBLIC xgboost-r)
+
 # Add all objects of xgboost-r to objxgboost
 target_sources(objxgboost INTERFACE $<TARGET_OBJECTS:xgboost-r>)
 
diff --git a/R-package/src/Makevars.in b/R-package/src/Makevars.in
index 9e7cbfed4c18..f42c94501b06 100644
--- a/R-package/src/Makevars.in
+++ b/R-package/src/Makevars.in
@@ -5,9 +5,12 @@ ENABLE_STD_THREAD=1
 
 CXX_STD = CXX17
 
-XGB_RFLAGS = -DXGBOOST_STRICT_R_MODE=1 -DDMLC_LOG_BEFORE_THROW=0\
-           -DDMLC_ENABLE_STD_THREAD=$(ENABLE_STD_THREAD) -DDMLC_DISABLE_STDIN=1\
-           -DDMLC_LOG_CUSTOMIZE=1
+XGB_RFLAGS = \
+    -DXGBOOST_STRICT_R_MODE=1 \
+    -DDMLC_LOG_BEFORE_THROW=0 \
+    -DDMLC_ENABLE_STD_THREAD=$(ENABLE_STD_THREAD) \
+    -DDMLC_DISABLE_STDIN=1 \
+    -DDMLC_LOG_CUSTOMIZE=1
 
 # disable the use of thread_local for 32 bit windows:
 ifeq ($(R_OSTYPE)$(WIN),windows)
@@ -15,9 +18,25 @@ ifeq ($(R_OSTYPE)$(WIN),windows)
 endif
 $(foreach v, $(XGB_RFLAGS), $(warning $(v)))
 
-PKG_CPPFLAGS=  -I$(PKGROOT)/include -I$(PKGROOT)/dmlc-core/include -I$(PKGROOT)/rabit/include -I$(PKGROOT) $(XGB_RFLAGS)
-PKG_CXXFLAGS= @OPENMP_CXXFLAGS@ @ENDIAN_FLAG@ -pthread $(CXX_VISIBILITY)
-PKG_LIBS = @OPENMP_CXXFLAGS@ @OPENMP_LIB@ @ENDIAN_FLAG@ @BACKTRACE_LIB@ -pthread
+PKG_CPPFLAGS = \
+    -I$(PKGROOT)/include \
+    -I$(PKGROOT)/dmlc-core/include \
+    -I$(PKGROOT)/rabit/include \
+    -I$(PKGROOT) \
+    $(XGB_RFLAGS)
+
+PKG_CXXFLAGS = \
+    @OPENMP_CXXFLAGS@ \
+    @ENDIAN_FLAG@ \
+    -pthread \
+    $(CXX_VISIBILITY)
+
+PKG_LIBS = \
+    @OPENMP_CXXFLAGS@ \
+    @OPENMP_LIB@ \
+    @ENDIAN_FLAG@ \
+    @BACKTRACE_LIB@ \
+    -pthread
 
 OBJECTS= \
     ./xgboost_R.o \
diff --git a/R-package/src/Makevars.win b/R-package/src/Makevars.win
index 7dfa415a43d1..1b620751f1d2 100644
--- a/R-package/src/Makevars.win
+++ b/R-package/src/Makevars.win
@@ -5,9 +5,12 @@ ENABLE_STD_THREAD=0
 
 CXX_STD = CXX17
 
-XGB_RFLAGS = -DXGBOOST_STRICT_R_MODE=1 -DDMLC_LOG_BEFORE_THROW=0\
-           -DDMLC_ENABLE_STD_THREAD=$(ENABLE_STD_THREAD) -DDMLC_DISABLE_STDIN=1\
-           -DDMLC_LOG_CUSTOMIZE=1
+XGB_RFLAGS = \
+    -DXGBOOST_STRICT_R_MODE=1 \
+    -DDMLC_LOG_BEFORE_THROW=0 \
+    -DDMLC_ENABLE_STD_THREAD=$(ENABLE_STD_THREAD) \
+    -DDMLC_DISABLE_STDIN=1 \
+    -DDMLC_LOG_CUSTOMIZE=1
 
 # disable the use of thread_local for 32 bit windows:
 ifeq ($(R_OSTYPE)$(WIN),windows)
@@ -15,9 +18,25 @@ ifeq ($(R_OSTYPE)$(WIN),windows)
 endif
 $(foreach v, $(XGB_RFLAGS), $(warning $(v)))
 
-PKG_CPPFLAGS=  -I$(PKGROOT)/include -I$(PKGROOT)/dmlc-core/include -I$(PKGROOT)/rabit/include -I$(PKGROOT) $(XGB_RFLAGS)
-PKG_CXXFLAGS= $(SHLIB_OPENMP_CXXFLAGS) -DDMLC_CMAKE_LITTLE_ENDIAN=1 $(SHLIB_PTHREAD_FLAGS) $(CXX_VISIBILITY)
-PKG_LIBS = $(SHLIB_OPENMP_CXXFLAGS)  -DDMLC_CMAKE_LITTLE_ENDIAN=1  $(SHLIB_PTHREAD_FLAGS) -lwsock32 -lws2_32
+PKG_CPPFLAGS = \
+    -I$(PKGROOT)/include \
+    -I$(PKGROOT)/dmlc-core/include \
+    -I$(PKGROOT)/rabit/include \
+    -I$(PKGROOT) \
+    $(XGB_RFLAGS)
+
+PKG_CXXFLAGS = \
+    $(SHLIB_OPENMP_CXXFLAGS) \
+    -DDMLC_CMAKE_LITTLE_ENDIAN=1 \
+    $(SHLIB_PTHREAD_FLAGS) \
+    $(CXX_VISIBILITY)
+
+PKG_LIBS = \
+    $(SHLIB_OPENMP_CXXFLAGS) \
+    -DDMLC_CMAKE_LITTLE_ENDIAN=1 \
+    $(SHLIB_PTHREAD_FLAGS) \
+    -lwsock32 \
+    -lws2_32
 
 OBJECTS= \
     ./xgboost_R.o \