diff --git a/mk/board_avr_sitl.mk b/mk/board_avr_sitl.mk
index 98f31487e1..8e85f64e61 100644
--- a/mk/board_avr_sitl.mk
+++ b/mk/board_avr_sitl.mk
@@ -39,7 +39,7 @@ ifneq ($(SYSTYPE),Darwin)
 LDFLAGS        +=   -Wl,--gc-sections -Wl,-Map -Wl,$(SKETCHMAP)
 endif
 
-LIBS = -lm -lpthread
+LIBS ?= -lm -lpthread
 
 ifeq ($(VERBOSE),)
 v = @
diff --git a/mk/board_linux.mk b/mk/board_linux.mk
index 031d835f99..31a7cb69e1 100644
--- a/mk/board_linux.mk
+++ b/mk/board_linux.mk
@@ -4,4 +4,5 @@ include $(MK_DIR)/find_tools.mk
 
 # Linux build is just the same as SITL for now
 OPTFLAGS = -O0
+LIBS = -lm -lpthread -lrt
 include $(MK_DIR)/board_avr_sitl.mk