diff --git a/rkward/rbackend/rpackages/rpackage_install.cmake.in b/rkward/rbackend/rpackages/rpackage_install.cmake.in
--- a/rkward/rbackend/rpackages/rpackage_install.cmake.in
+++ b/rkward/rbackend/rpackages/rpackage_install.cmake.in
@@ -17,16 +17,16 @@
 	ENDIF(DESTDIR)
 	EXECUTE_PROCESS(
 		COMMAND @R_EXECUTABLE@ CMD INSTALL ${TIMESTAMPARG} -c -l ${R_LIBDIR} "@CMAKE_CURRENT_SOURCE_DIR@/rkward" "@CMAKE_CURRENT_SOURCE_DIR@/rkwardtests"
-		WORKING_DIRECTORY @CMAKE_CURRENT_BINARY_DIR@
+		WORKING_DIRECTORY "@CMAKE_CURRENT_BINARY_DIR@"
 		RESULT_VARIABLE R_LIB_INSTALL_EXIT_CODE
 	)
 ELSE(WIN32)
 	EXECUTE_PROCESS(
-		COMMAND mkdir -p @CMAKE_CURRENT_BINARY_DIR@/tmp ${DESTDIR}/@R_LIBDIR@
+		COMMAND mkdir -p "@CMAKE_CURRENT_BINARY_DIR@/tmp" ${DESTDIR}/@R_LIBDIR@
 	)
 	EXECUTE_PROCESS(
-		COMMAND env TMPDIR=@CMAKE_CURRENT_BINARY_DIR@/tmp @R_EXECUTABLE@ CMD INSTALL ${TIMESTAMPARG} -c -l ${DESTDIR}/@R_LIBDIR@ "@CMAKE_CURRENT_SOURCE_DIR@/rkward" "@CMAKE_CURRENT_SOURCE_DIR@/rkwardtests"
-		WORKING_DIRECTORY @CMAKE_CURRENT_BINARY_DIR@
+		COMMAND env TMPDIR="@CMAKE_CURRENT_BINARY_DIR@/tmp" @R_EXECUTABLE@ CMD INSTALL ${TIMESTAMPARG} -c -l ${DESTDIR}/@R_LIBDIR@ "@CMAKE_CURRENT_SOURCE_DIR@/rkward" "@CMAKE_CURRENT_SOURCE_DIR@/rkwardtests"
+		WORKING_DIRECTORY "@CMAKE_CURRENT_BINARY_DIR@"
 		RESULT_VARIABLE R_LIB_INSTALL_EXIT_CODE
 	)
 ENDIF(WIN32)