diff --git a/defs/gmake.mk b/defs/gmake.mk
index af8c8a651f..6f8c101d74 100644
--- a/defs/gmake.mk
+++ b/defs/gmake.mk
@@ -2,6 +2,7 @@
 gnumake = yes
 override gnumake_recursive := $(if $(findstring n,$(firstword $(MFLAGS))),,+)
 override mflags := $(filter-out -j%,$(MFLAGS))
+MSPECOPT += $(if $(filter -j%,$(MFLAGS)),-j)
 
 CHECK_TARGETS := great exam love check test check% test% btest%
 # expand test targets, and those dependents