diff --git a/code/__DEFINES/_flags/_flags.dm b/code/__DEFINES/_flags/_flags.dm
index ffa3f1c751..cdf2fc27c9 100644
--- a/code/__DEFINES/_flags/_flags.dm
+++ b/code/__DEFINES/_flags/_flags.dm
@@ -9,7 +9,12 @@
 #define DISABLE_BITFIELD(variable, flag) (variable &= ~(flag))
 #define CHECK_BITFIELD(variable, flag) (variable & (flag))
 #define TOGGLE_BITFIELD(variable, flag) (variable ^= (flag))
-
+#define COPY_SPECIFIC_BITFIELDS(a,b,flags)\
+	do{
+		var/_old = a & ~(flags);\
+		var/_cleaned = b & (flags);\
+		a = _old | _cleaned
+	} while(0);
 #define CHECK_MULTIPLE_BITFIELDS(flagvar, flags) (((flagvar) & (flags)) == (flags))
 
 GLOBAL_LIST_INIT(bitflags, list(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768))