diff --git a/bootstrap.d/13-kernel.sh b/bootstrap.d/13-kernel.sh
index f6ee18a..73c0821 100644
--- a/bootstrap.d/13-kernel.sh
+++ b/bootstrap.d/13-kernel.sh
@@ -5,6 +5,11 @@
 # Load utility functions
 . ./functions.sh
 
+# Use kali kernel src if nexmon is enabled
+if [ "$ENABLE_NEXMON" = true ] ; then
+  KERNEL_URL="${NEXMON_URL}"
+fi
+
 # Fetch and build latest raspberry kernel
 if [ "$BUILD_KERNEL" = true ] ; then
   # Setup source directory
@@ -23,11 +28,6 @@ if [ "$BUILD_KERNEL" = true ] ; then
     # Create temporary directory for kernel sources
     temp_dir=$(as_nobody mktemp -d)
 	
-	# Use kali kernel src if nexmon is enabled
-	if [ "$ENABLE_NEXMON" = true ] ; then
-	  KERNEL_URL="${NEXMON_URL}"
-    fi
-	
     # Fetch current RPi2/3 kernel sources
     if [ -z "${KERNEL_BRANCH}" ] ; then
       as_nobody -H git -C "${temp_dir}" clone --depth=1 "${KERNEL_URL}" linux
diff --git a/bootstrap.d/15-rpi-config.sh b/bootstrap.d/15-rpi-config.sh
index 4328de4..a968d28 100644
--- a/bootstrap.d/15-rpi-config.sh
+++ b/bootstrap.d/15-rpi-config.sh
@@ -116,6 +116,8 @@ if [ "$RPI_MODEL" = 0 ] || [ "$RPI_MODEL" = 3 ] || [ "$RPI_MODEL" = 3P ] ; then
     # Install tools
     install_readonly "${R}/tmp/pi-bluetooth/usr/bin/btuart" "${R}/usr/bin/btuart"
     install_readonly "${R}/tmp/pi-bluetooth/usr/bin/bthelper" "${R}/usr/bin/bthelper"
+	chmod +x "${R}/usr/bin/bthelper"
+	chmod +x "${R}/usr/bin/btuart"
 
     # Install bluetooth udev rule
     install_readonly "${R}/tmp/pi-bluetooth/lib/udev/rules.d/90-pi-bluetooth.rules" "${LIB_DIR}/udev/rules.d/90-pi-bluetooth.rules"
diff --git a/rpi23-gen-image.sh b/rpi23-gen-image.sh
index 8a8fe28..42024a1 100755
--- a/rpi23-gen-image.sh
+++ b/rpi23-gen-image.sh
@@ -351,6 +351,11 @@ else # Raspberry PI 1,1P,2 without Wifi and bluetooth onboard
   fi
 fi
 
+if [ "$BUILD_KERNEL" = false ] && [ "$ENABLE_NEXMON" = true ]; then
+  echo "error: You have to compile kernel sources, if you want to enable nexmon"
+  exit 1
+fi
+
 # Prepare date string for default image file name
 DATE="$(date +%Y-%m-%d)"
 if [ -z "$KERNEL_BRANCH" ] ; then