diff --git a/targets/ARCH/rfsimulator/README.md b/targets/ARCH/rfsimulator/README.md
index c3843ec4a3..89964decd5 100644
--- a/targets/ARCH/rfsimulator/README.md
+++ b/targets/ARCH/rfsimulator/README.md
@@ -46,6 +46,7 @@ $OPENAIR_DIR/targets/bin/conf2uedata -c $OPENAIR_DIR/openair3/NAS/TOOLS/ue_eurec
 ```
 ## 5G case
 After regular build, add the simulation driver
+(don't use ./build_oai -w SIMU until we merge 4G and 5G branches)
 ```bash
 cd ran_build/build
 make rfsimulator