diff --git a/test/regression/cocotb/benchmark.Makefile b/test/regression/cocotb/benchmark.Makefile
index 5c89d3785..9962315fb 100644
--- a/test/regression/cocotb/benchmark.Makefile
+++ b/test/regression/cocotb/benchmark.Makefile
@@ -15,6 +15,7 @@ SIM_BUILD = build/benchmark
 # Yosys/Amaranth borkedness workaround
 ifeq ($(SIM),verilator)
   EXTRA_ARGS += -Wno-CASEINCOMPLETE -Wno-CASEOVERLAP -Wno-WIDTHEXPAND -Wno-WIDTHTRUNC
+  BUILD_ARGS += -j`nproc`
 endif
 
 ifeq ($(TRACES),1)
diff --git a/test/regression/cocotb/signature.Makefile b/test/regression/cocotb/signature.Makefile
index 74b803083..b4f690635 100644
--- a/test/regression/cocotb/signature.Makefile
+++ b/test/regression/cocotb/signature.Makefile
@@ -15,6 +15,7 @@ SIM_BUILD = build/signature
 # Yosys/Amaranth borkedness workaround
 ifeq ($(SIM),verilator)
   EXTRA_ARGS += -Wno-CASEINCOMPLETE -Wno-CASEOVERLAP -Wno-WIDTHEXPAND -Wno-WIDTHTRUNC
+  BUILD_ARGS += -j`nproc`
 endif
 
 ifeq ($(TRACES),1)
diff --git a/test/regression/cocotb/test.Makefile b/test/regression/cocotb/test.Makefile
index bda120bc1..210618067 100644
--- a/test/regression/cocotb/test.Makefile
+++ b/test/regression/cocotb/test.Makefile
@@ -15,6 +15,7 @@ SIM_BUILD = build/test
 # Yosys/Amaranth borkedness workaround
 ifeq ($(SIM),verilator)
   EXTRA_ARGS += -Wno-CASEINCOMPLETE -Wno-CASEOVERLAP -Wno-WIDTHEXPAND -Wno-WIDTHTRUNC
+  BUILD_ARGS += -j`nproc`
 endif
 
 ifeq ($(TRACES),1)