diff --git a/master.inc b/master.inc
index 26efb7a..7801b6c 100644
--- a/master.inc
+++ b/master.inc
@@ -92,6 +92,7 @@ pathfix.py -i "%{__python3} %{py3_shbang_opts}" -n -p \
 %{make} distclean
 
 %{make} "${EXTRA_LINUX_CONFIG[@]}" %{target_config}
+cp .config .config.%{target_config}
 
 tar -xf %{SOURCE2} -C .
 cp -vr kernel-tfg/{configure-linux.sh,extra-configs} .
@@ -105,7 +106,7 @@ make olddefconfig
 # 0 means no diff /diff        [1/4]
 # 1 means diff
 # 2 means trouble
-diff .config .config.old || echo "Diffing done"
+diff .config .config.%{target_config} || echo "Diffing done"
 
 %build
 %{make} %{?_smp_mflags} PYTHON=%{__python3} %{make_targets}