--- configure.sv	2019-04-25 17:48:18.713003500 +0200
+++ configure	2019-04-25 17:51:22.940270700 +0200
@@ -1,4 +1,4 @@
-#! /bin/sh
+#! /bin/sh -x
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.69 for stringi 1.4.
 #
@@ -2413,7 +2413,7 @@
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for R >= 3.1.0 for C++11 use" >&5
 $as_echo_n "checking for R >= 3.1.0 for C++11 use... " >&6; }
-R_GE_31=`"${R_PATH}" --vanilla --slave -e 'cat(if (getRversion() >= numeric_version("3.1.0")) "yes" else "no")'`
+R_GE_31=`"${R_PATH}" --vanilla --slave -e "cat(if (getRversion() >= numeric_version('3.1.0')) 'yes' else 'no')"`
 if test "x$R_GE_31" = "xyes"; then
    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
@@ -2428,7 +2428,7 @@
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for R < 3.4.0 for CXX1X flag use" >&5
 $as_echo_n "checking for R < 3.4.0 for CXX1X flag use... " >&6; }
-R_GE_34=`"${R_PATH}" --vanilla --slave -e 'cat(if (getRversion() >= numeric_version("3.4.0")) "yes" else "no")'`
+R_GE_34=`"${R_PATH}" --vanilla --slave -e "cat(if (getRversion() >= numeric_version('3.4.0')) 'yes' else 'no')"`
 if test "x$R_GE_34" = "xyes"; then
    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
@@ -4891,8 +4891,8 @@
 if test $ICU_FOUND = 0; then
    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether we can fetch icudt" >&5
 $as_echo_n "checking whether we can fetch icudt... " >&6; }
-   "${R_PATH}" --vanilla --slave -e "setwd(\"src/\"); \
-            source(\"../R/install.R\"); \
+   "${R_PATH}" --vanilla --slave -e "setwd('src/'); \
+            source('../R/install.R'); \
             if (identical(FALSE,stri_download_icudt(\"${ICUDT_DIR}\",${ICU_BUNDLE_VERSION}))) \
                 stop(\"Stopping on error\")"
    if test $? -ne 0; then