diff --git a/flow/scripts/variables.mk b/flow/scripts/variables.mk
index 728ec4bc82..6567737158 100644
--- a/flow/scripts/variables.mk
+++ b/flow/scripts/variables.mk
@@ -111,8 +111,8 @@ OPENROAD_IS_VALID := $(if $(OPENROAD_EXE),$(shell test -x $(OPENROAD_EXE) && ech
 export OPENROAD_ARGS = -no_init -threads $(NUM_CORES) $(OR_ARGS)
 export OPENROAD_CMD = $(OPENROAD_EXE) -exit $(OPENROAD_ARGS)
 export OPENROAD_NO_EXIT_CMD = $(OPENROAD_EXE) $(OPENROAD_ARGS)
-export OPENROAD_GUI_CMD = $(OPENROAD_EXE) -gui $(OR_ARGS)
-export OPENROAD_WEB_CMD = $(OPENROAD_EXE) -web $(OR_ARGS)
+export OPENROAD_GUI_CMD = $(OPENROAD_EXE) -gui -threads $(NUM_CORES) $(OR_ARGS)
+export OPENROAD_WEB_CMD = $(OPENROAD_EXE) -web -threads $(NUM_CORES) $(OR_ARGS)
 
 ifneq (${IN_NIX_SHELL},)
   YOSYS_EXE ?= $(shell command -v yosys)