diff --git a/linux-tkg-config/prepare b/linux-tkg-config/prepare
index 975d832..f9e110e 100644
--- a/linux-tkg-config/prepare
+++ b/linux-tkg-config/prepare
@@ -385,7 +385,7 @@ _define_kernel_abs_paths() {
 
   source "$_where"/BIG_UGLY_FROGMINER
 
-  if [ -n "$_kernel_work_folder_abs" ]; then
+  if [ -z "$_kernel_work_folder_abs" ]; then
     _kernel_work_folder_abs="$_where/$_kernel_work_folder/linux-src-git"
     if [[ "$_kernel_work_folder" == /* ]]; then
       _kernel_work_folder_abs="$_kernel_work_folder/linux-tkg/linux-src-git"
@@ -393,7 +393,7 @@ _define_kernel_abs_paths() {
     echo -e "_kernel_work_folder_abs=\"$_kernel_work_folder_abs\"" >> "$_where"/BIG_UGLY_FROGMINER
   fi
 
-  if [ -n "$_kernel_source_folder_abs" ]; then
+  if [ -z "$_kernel_source_folder_abs" ]; then
     _kernel_source_folder_abs="$_where/$_kernel_source_folder/linux-kernel.git"
     if [[ "$_kernel_source_folder" == /* ]]; then
       _kernel_source_folder_abs="$_kernel_source_folder/linux-tkg/linux-kernel.git"