diff --git a/flow/designs/sky130hd/microwatt/config.mk b/flow/designs/sky130hd/microwatt/config.mk
index 09ef02ea17..37d60ed2a1 100644
--- a/flow/designs/sky130hd/microwatt/config.mk
+++ b/flow/designs/sky130hd/microwatt/config.mk
@@ -23,7 +23,6 @@ export ADDITIONAL_LIBS = $(wildcard $(microwatt_DIR)/lib/*.lib)
 
 export SYNTH_HIERARCHICAL = 1
 
-export RTLMP_BOUNDARY_WT = 0
 export MACRO_PLACE_HALO = 100 100
 export MACRO_PLACE_CHANNEL = 200 200