diff --git a/unit_tests/Makefile b/unit_tests/Makefile
index c4ccc855e5..fd9a24a4c8 100644
--- a/unit_tests/Makefile
+++ b/unit_tests/Makefile
@@ -209,7 +209,7 @@ AOPT =
 TOPT = -mthumb -DTHUMB
 
 # Define C warning options here
-CWARN = -Wall -Wextra -Wstrict-prototypes -pedantic -Wmissing-prototypes -Wold-style-definition -Wextra
+CWARN = -Wall -Wextra -Wstrict-prototypes -pedantic -Wmissing-prototypes -Wold-style-definition
 
 # Define C++ warning options here
 CPPWARN = -Wall -Wextra