diff --git a/Dockerfile b/Dockerfile
index b00d5fc..ddb7789 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -55,7 +55,7 @@ RUN \
         pattern="fixme:win:NtUserLockWindowUpdate ((nil))"; \
         # The amount of times the pattern should occur for the process to be considered stuck
         patternCount=2; \
-        output=$( \
+        output="$( \
             sed \
                 # Handle exit hints
                 -e "s/^exit \([[:digit:]]\+\)$/\1/; t end;" \
@@ -66,45 +66,46 @@ RUN \
                 # Branch "stuck": delete output and exit with code 42
                 -e ":stuck s/.*//; q42;" \
                 # Branch "end": exit with code 0
-                -e ":end q;"); \
+                -e ":end q;")"; \
+        exitCode="$?"; \
         exitCode=$?; \
         # Kill installer if it got stuck (according to console output)
-        [ $exitCode -eq 42 ] && pkill -9 MDK537.exe; \
+        [ "$exitCode" -eq 42 ] && pkill -9 MDK537.exe; \
         # Use `sed`s exit code if non-zero
-        [ $exitCode -ne 0 ] && exit $exitCode; \
+        [ "$exitCode" -ne 0 ] && exit $exitCode; \
         # Use `sed`s output otherwise
-        [ $exitCode -eq 0 ] && exit $output; \
+        [ "$exitCode" -eq 0 ] && exit $output; \
     }; \
     # Run actual MDK537 installer
     install_keil() { \
         echo "Starting ARM Keil installation"; \
-        try=$1; \
+        try="$1"; \
         # Run installer asynchronously
         { \
             { 2>&1 WINEDEBUG=+all,trace-all,warn-all /usr/bin/entrypoint wine MDK537.exe --batch-install || echo "exit $?"; } \
                 # Write output to `log.txt`
-                | { [ $DEBUG -eq 1 ] && tee log.txt || cat; } \
+                | { [ "$DEBUG" -eq 1 ] && tee log.txt || cat; } \
                 # Pipe stdout and stderr to `handle_output` function
                 | handle_output & \
         }; \
-        pid=$!; \
+        pid="$!"; \
         # Continuously display screenshots and iteration number
-        [ $DEBUG -eq 1 ] \
+        [ "$DEBUG" -eq 1 ] \
         && { \
             { \
                 x=0; \
                 maxCount=120; \
-                while ps -p $pid > /dev/null && [ $x -ne $maxCount ]; do \
+                while ps -p "$pid" > /dev/null && [ "$x" -ne "$maxCount" ]; do \
                     # Create screenshot and print it to the console
-                    fileName=screens/install-try$try-$x.png; \
-                    import -window root $fileName; \
-                    tiv -w 10000 -h 10000 $fileName; \
+                    fileName="screens/install-try$try-$x.png"; \
+                    import -window root "$fileName"; \
+                    tiv -w 10000 -h 10000 "$fileName"; \
                     x=$(bash -c "declare -i x=$x+1; echo "'$x'); \
                     echo $x; \
                     sleep 1; \
                 done; \
                 # Kill installer after timeout indicated by `maxCount`
-                [ $x -eq $maxCount ] && { pkill -9 MDK537.exe; mv log.txt logs/timeout-try$try.log; }; \
+                [ "$x" -eq "$maxCount" ] && { pkill -9 MDK537.exe; mv log.txt "logs/timeout-try$try.log"; }; \
             } & \
         }; \
         wait $pid; \
@@ -114,12 +115,12 @@ RUN \
         && [ -f log.txt ] \
         && { \
             # Move logs to location based on exit code
-            [ $exitCode -eq 0 ] && mv log.txt logs/success-try$try.log; \
-            [ $exitCode -eq 42 ] && mv log.txt logs/timeout-handled-try$try.log; \
-            [ $exitCode -ne 0 ] && mv log.txt logs/fail-try$try.log; \
+            [ "$exitCode" -eq 0 ] && mv log.txt "logs/success-try$try.log"; \
+            [ "$exitCode" -eq 42 ] && mv log.txt "logs/timeout-handled-try$try.log"; \
+            [ "$exitCode" -ne 0 ] && mv log.txt "logs/fail-try$try.log"; \
         }; \
-        [ $exitCode -ne 0 ] && { \
-            [ $exitCode -eq 42 ] && echo "The installation got stuck" || \
+        [ "$exitCode" -ne 0 ] && { \
+            [ "$exitCode" -eq 42 ] && echo "The installation got stuck" || \
             echo "The installation failed"; \
         } || \
         echo "The installation was successful"; \
@@ -132,16 +133,16 @@ RUN \
     # Create job for waiting for Xvfb to start
     watchStarting="$(mktemp)"; \
     { 2>&1 inotifywait -e create /tmp/.X11-unix/; } | { sed -u -e "/^Watches established.\$/e rm \"$watchStarting\""; } & \
-    resolver=$!; \
+    resolver="$!"; \
     while [ -f "$watchStarting" ]; do true; done; \
     { \
         # Improve arguments for screenshots
-        ARGS=$([ $DEBUG -eq 1 ] && echo "-screen 0 640x480x24 -dpi 192" || echo ""); \
+        ARGS="$([ $DEBUG -eq 1 ] && echo "-screen 0 640x480x24 -dpi 192" || echo "")"; \
         Xvfb ${DISPLAY} ${ARGS} & \
     }; \
-    displayPID=$!; \
+    displayPID="$!"; \
     # Wait for Xvfb to start
-    wait $resolver; \
+    wait "$resolver"; \
     y=0; \
     while ! \
         install_keil \
@@ -152,27 +153,27 @@ RUN \
         # Increase counter
         y=$(bash -c "declare -i y=$y+1; echo "'$y'); \
     done && \
-    kill -9 $displayPID > /dev/null 2>&1; \
+    kill -9 "$displayPID" > /dev/null 2>&1; \
     # Delete unfinished installations
     rm -rf "$(/usr/bin/entrypoint winepath 'C:\Keil_v5')/Backup."*; \
     rm MDK537.exe; \
     rm -f /tmp/.X*-lock;
 
 RUN \
-    keilConfig=$(/usr/bin/entrypoint winepath 'C:\Keil_v5\TOOLS.INI') && \
+    keilConfig="$(/usr/bin/entrypoint winepath 'C:\Keil_v5\TOOLS.INI')" && \
     winAppData="$(/usr/bin/entrypoint wine cmd.exe /c 'echo %LOCALAPPDATA%' | tr -d '\r' | sed 's/\\/\\\\/g')" && \
     packDir="$winAppData"'\Arm\Packs' && \
-    sed -i '/^RTEPATH=/d' $keilConfig && \
-    echo 'RTEPATH="'"$packDir"'"' | sed -i '/\[UV2\]/ r /dev/stdin' $keilConfig
+    sed -i '/^RTEPATH=/d' "$keilConfig" && \
+    echo 'RTEPATH="'"$packDir"'"' | sed -i '/\[UV2\]/ r /dev/stdin' "$keilConfig"
 
 RUN \
-    wget ${PACK_URL} --progress=bar:force:noscroll --no-check-certificate -O InES.pack; \
+    wget "${PACK_URL}" --progress=bar:force:noscroll --no-check-certificate -O InES.pack; \
     /usr/bin/entrypoint xvfb-run wine 'C:\Keil_v5\UV4\PackUnzip.exe' --embedded --agree-license InES.pack & \
-    pid=$!; \
-    wait $pid; \
-    pkill -P -9 $pid > /dev/null 2>&1; \
-    kill -9 $pid > /dev/null 2>&1; \
-    kill -9 $displayPID > /dev/null 2>&1; \
+    pid="$!"; \
+    wait "$pid"; \
+    pkill -P -9 "$pid" > /dev/null 2>&1; \
+    kill -9 "$pid" > /dev/null 2>&1; \
+    kill -9 "$displayPID" > /dev/null 2>&1; \
     rm InES.pack; \
     rm -f /tmp/.X*-lock;