diff --git a/bin/impl/load-env.sh b/bin/impl/load-env.sh
index a750727..a58eabc 100755
--- a/bin/impl/load-env.sh
+++ b/bin/impl/load-env.sh
@@ -122,10 +122,12 @@ fi
 hash shasum 2>/dev/null || { echo >&2 "shasum must be installed & on PATH. Aborting."; exit 1; }
 hash sed 2>/dev/null || { echo >&2 "sed must be installed & on PATH. Aborting."; exit 1; }
 
-if [[ $OSTYPE =~ ^darwin ]]; then
-  export SED="sed -i .bak"
-else
+if sed --version >/dev/null 2>&1; then
+  # GNU sed supports --version and -i without a backup suffix parameter
   export SED="sed -i"
+else
+  # BSD sed requires backup suffix parameter with -i
+  export SED="sed -i .bak"
 fi
 
 # load-env.sh
diff --git a/bin/impl/run/hadoop.sh b/bin/impl/run/hadoop.sh
index 17be5d4..e465bf2 100755
--- a/bin/impl/run/hadoop.sh
+++ b/bin/impl/run/hadoop.sh
@@ -27,7 +27,13 @@ trap 'echo "[ERROR] Error occurred at $BASH_SOURCE:$LINENO command: $BASH_COMMAN
 
 "$HADOOP_HOME"/bin/hdfs namenode -format
 "$HADOOP_HOME"/sbin/start-dfs.sh
-"$HADOOP_HOME"/sbin/start-yarn.sh
+# Yarn won't start on newer versions of Java
+jver=$("$JAVA_HOME"/bin/java -version 2>&1 | grep version | cut -f2 -d'"' | cut -f1 -d.)
+if [[ $jver -gt 11 ]]; then
+  echo "Skipping yarn because it doesn't start on Java $jver"
+else
+  "$HADOOP_HOME"/sbin/start-yarn.sh
+fi
 
 namenode_port=9870
 if [[ $HADOOP_VERSION =~ ^2\..*$ ]]; then
diff --git a/bin/impl/util.sh b/bin/impl/util.sh
index f5a6344..b0c3719 100755
--- a/bin/impl/util.sh
+++ b/bin/impl/util.sh
@@ -111,7 +111,9 @@ function setup_component() {
 }
 
 function save_console_fd {
-  if [[ -z $UNO_CONSOLE_FD && ! $OSTYPE =~ ^darwin ]]; then
+  # this requires at least bash 4.1
+  local v=("${BASH_VERSINFO[@]}")
+  if [[ -z $UNO_CONSOLE_FD ]] && (( v[0]>4 || (v[0]==4 && v[1]>=1) )); then
     # Allocate an unused file descriptor and make it dup stdout
     # https://stackoverflow.com/a/41620630/7298689
     exec {UNO_CONSOLE_FD}>&1