--- a/icu4c.SlackBuild	2023-04-14 19:03:17.555070455 +0000
+++ b/icu4c.SlackBuild	2023-04-16 10:43:08.364203579 +0000
@@ -62,6 +62,12 @@ elif [ "$ARCH" = "s390" ]; then
 elif [ "$ARCH" = "x86_64" ]; then
   SLKCFLAGS="-O2 -fPIC"
   LIBDIRSUFFIX="64"
+elif [ "$ARCH" = "aarch64" ]; then
+  SLKCFLAGS="-O2 -fPIC"
+  LIBDIRSUFFIX="64"
+elif [ "$ARCH" = "riscv64" ]; then
+  SLKCFLAGS="-O2 -fPIC"
+  LIBDIRSUFFIX="64"
 else
   SLKCFLAGS="-O2"
   LIBDIRSUFFIX=""
@@ -81,8 +87,10 @@ find . \
   -o -perm 400 \) -exec chmod 644 {} \+
 
 cd source/
+  CC=gcc \
+  CXX=g++ \
   CFLAGS="$SLKCFLAGS -Wno-gnu-line-marker" \
-  CXXFLAGS="$SLKCFLAGS -Wno-gnu-line-marker" \
+  CXXFLAGS="$SLKCFLAGS -Wno-gnu-line-marker -std=c++11" \
   ./configure \
     --prefix=/usr \
     --libdir=/usr/lib${LIBDIRSUFFIX} \