diff --git a/src/proc.sh b/src/proc.sh
index 56b2466..129d70f 100644
--- a/src/proc.sh
+++ b/src/proc.sh
@@ -10,19 +10,20 @@ set -Eeuo pipefail
 : "${DEF_MODEL:="qemu64"}"
 
 CLOCKSOURCE="tsc"
-[[ "${ARCH,,}" == "arm64" ]] && CLOCKSOURCE="arch_sys_counter"
+[[ "${ARCH,,}" == "arm64" ]] && CLOCKSOURCE="arch_sys_counter"
 CLOCK="/sys/devices/system/clocksource/clocksource0/current_clocksource"
 
 if [ ! -f "$CLOCK" ]; then
   warn "file \"$CLOCK\" cannot not found?"
 else
   result=$(<"$CLOCK")
+  result="${result//[![:print:]]/}"
   case "${result,,}" in
     "${CLOCKSOURCE,,}" ) ;;
     "kvm-clock" ) info "Nested KVM virtualization detected.." ;;
     "hyperv_clocksource_tsc_page" ) info "Nested Hyper-V virtualization detected.." ;;
-    "hpet" ) warn "unsupported clock source detected: '$result'. Please set host clock source to '$CLOCKSOURCE'" ;;
-    *) warn "unexpected clock source detected: '$result'. Please set host clock source to '$CLOCKSOURCE'" ;;
+    "hpet" ) warn "unsupported clock source detected: '$result'. Please set host clock source to '$CLOCKSOURCE'." ;;
+    *) warn "unexpected clock source detected: '$result'. Please set host clock source to '$CLOCKSOURCE'." ;;
   esac
 fi