diff --git a/simulator/Makefile b/simulator/Makefile
index 61daad42ed..77842a6ae8 100644
--- a/simulator/Makefile
+++ b/simulator/Makefile
@@ -19,7 +19,7 @@ ifeq ($(USE_OPT),)
 # this config producec a smaller binary file
 # 7.3 compiler would want -Wno-error=implicit-fallthrough while 6.4 does not know about it
 # see https://github.com/rusefi/rusefi/issues/517
-  USE_OPT = -Wall -O2    -Wno-error=implicit-fallthrough       -Werror-implicit-function-declaration -Werror -Wno-error=pointer-sign -Wno-error=unused-function -Wno-error=unused-variable -Wno-error=sign-compare -Wno-error=unused-parameter -Wno-error=missing-field-initializers -Wno-error=write-strings -Wno-error=strict-aliasing
+  USE_OPT = -Wall -O2    -Wno-error=implicit-fallthrough       -Werror-implicit-function-declaration -Werror -Wno-error=pointer-sign -Wno-error=unused-function -Wno-error=unused-variable -Wno-error=sign-compare -Wno-error=unused-parameter -Werror=missing-field-initializers -Wno-error=write-strings -Wno-error=strict-aliasing
 
 	ifeq ($(OS),Windows_NT)
 	else
diff --git a/unit_tests/Makefile b/unit_tests/Makefile
index 9285091d44..c4ccc855e5 100644
--- a/unit_tests/Makefile
+++ b/unit_tests/Makefile
@@ -12,7 +12,7 @@ ifeq ($(USE_OPT),)
 #
 # -O2 is needed for mingw, without it there is a linking issue to isnanf?!?!
   #USE_OPT = $(RFLAGS) -O2 -fgnu89-inline -ggdb -fomit-frame-pointer -falign-functions=16 -std=gnu99 -Werror-implicit-function-declaration -Werror -Wno-error=pointer-sign -Wno-error=unused-function -Wno-error=unused-variable -Wno-error=sign-compare -Wno-error=unused-parameter -Wno-error=missing-field-initializers
-  USE_OPT = -c -Wall -O0 -ggdb -g3
+  USE_OPT = -c -Wall -O0 -ggdb -g3 -Werror=missing-field-initializers
 endif
 
 # C specific options here (added to USE_OPT).