diff --git a/code/__DEFINES/__513_compatibility.dm b/code/__DEFINES/__513_compatibility.dm
new file mode 100644
index 0000000000..12577fb68b
--- /dev/null
+++ b/code/__DEFINES/__513_compatibility.dm
@@ -0,0 +1,32 @@
+
+#if DM_VERSION < 513
+
+#define ismovableatom(A) (istype(A, /atom/movable))
+
+#define islist(L) (istype(L, /list))
+
+#define CLAMP01(x) (CLAMP(x, 0, 1))
+
+#define CLAMP(CLVALUE,CLMIN,CLMAX) ( max( (CLMIN), min((CLVALUE), (CLMAX)) ) )
+
+#define ATAN2(x, y) ( !(x) && !(y) ? 0 : (y) >= 0 ? arccos((x) / sqrt((x)*(x) + (y)*(y))) : -arccos((x) / sqrt((x)*(x) + (y)*(y))) )
+
+#define TAN(x) (sin(x) / cos(x))
+
+#define arctan(x) (arcsin(x/sqrt(1+x*x)))
+
+//////////////////////////////////////////////////
+
+#else
+
+#define ismovableatom(A) ismovable(A)
+
+#define CLAMP01(x) clamp(x, 0, 1)
+
+#define CLAMP(CLVALUE, CLMIN, CLMAX) clamp(CLVALUE, CLMIN, CLMAX)
+
+#define TAN(x) tan(x)
+
+#define ATAN2(x, y) arctan(x, y)
+
+#endif
diff --git a/code/__DEFINES/is_helpers.dm b/code/__DEFINES/is_helpers.dm
index 9f69da0154..0dee8bd1e8 100644
--- a/code/__DEFINES/is_helpers.dm
+++ b/code/__DEFINES/is_helpers.dm
@@ -1,11 +1,7 @@
 // simple is_type and similar inline helpers
 
-#define islist(L) (istype(L, /list))
-
 #define in_range(source, user) (get_dist(source, user) <= 1 && (get_step(source, 0)?:z) == (get_step(user, 0)?:z))
 
-#define ismovableatom(A) (istype(A, /atom/movable))
-
 #define isatom(A) (isloc(A))
 
 #define isweakref(D) (istype(D, /datum/weakref))
@@ -246,4 +242,4 @@ GLOBAL_LIST_INIT(glass_sheet_types, typecacheof(list(
 
 #define isblobmonster(O) (istype(O, /mob/living/simple_animal/hostile/blob))
 
-#define isshuttleturf(T) (length(T.baseturfs) && (/turf/baseturf_skipover/shuttle in T.baseturfs))
+#define isshuttleturf(T) (length(T.baseturfs) && (/turf/baseturf_skipover/shuttle in T.baseturfs))
\ No newline at end of file
diff --git a/code/__DEFINES/maths.dm b/code/__DEFINES/maths.dm
index 5bce51293f..ad93dd2d54 100644
--- a/code/__DEFINES/maths.dm
+++ b/code/__DEFINES/maths.dm
@@ -16,7 +16,6 @@
 #define TICK_USAGE_TO_MS(starting_tickusage) (TICK_DELTA_TO_MS(TICK_USAGE_REAL - starting_tickusage))
 
 #define PERCENT(val) (round((val)*100, 0.1))
-#define CLAMP01(x) (CLAMP(x, 0, 1))
 
 //time of day but automatically adjusts to the server going into the next day within the same round.
 //for when you need a reliable time number that doesn't depend on byond time.
@@ -30,17 +29,12 @@
 // round() acts like floor(x, 1) by default but can't handle other values
 #define FLOOR(x, y) ( round((x) / (y)) * (y) )
 
-#define CLAMP(CLVALUE,CLMIN,CLMAX) ( max( (CLMIN), min((CLVALUE), (CLMAX)) ) )
-
 // Similar to clamp but the bottom rolls around to the top and vice versa. min is inclusive, max is exclusive
 #define WRAP(val, min, max) ( min == max ? min : (val) - (round(((val) - (min))/((max) - (min))) * ((max) - (min))) )
 
 // Real modulus that handles decimals
 #define MODULUS(x, y) ( (x) - (y) * round((x) / (y)) )
 
-// Tangent
-#define TAN(x) (sin(x) / cos(x))
-
 // Cotangent
 #define COT(x) (1 / TAN(x))
 
@@ -50,8 +44,6 @@
 // Cosecant
 #define CSC(x) (1 / sin(x))
 
-#define ATAN2(x, y) ( !(x) && !(y) ? 0 : (y) >= 0 ? arccos((x) / sqrt((x)*(x) + (y)*(y))) : -arccos((x) / sqrt((x)*(x) + (y)*(y))) )
-
 // Greatest Common Divisor - Euclid's algorithm
 /proc/Gcd(a, b)
 	return b ? Gcd(b, (a) % (b)) : a
@@ -207,4 +199,4 @@
 #define LORENTZ_CUMULATIVE_DISTRIBUTION(x, y, s) ( (1/PI)*TORADIANS(arctan((x-y)/s)) + 1/2 )
 
 #define RULE_OF_THREE(a, b, x) ((a*x)/b)
-// )
+// )
\ No newline at end of file
diff --git a/code/__HELPERS/_lists.dm b/code/__HELPERS/_lists.dm
index fed283adcd..38b779427c 100644
--- a/code/__HELPERS/_lists.dm
+++ b/code/__HELPERS/_lists.dm
@@ -514,7 +514,7 @@
 		used_key_list[input_key] = 1
 	return input_key
 
-#if DM_VERSION > 512
+#if DM_VERSION > 513
 #error Remie said that lummox was adding a way to get a lists
 #error contents via list.values, if that is true remove this
 #error otherwise, update the version and bug lummox
@@ -564,4 +564,4 @@
 		if(key in L1)
 			L1[key] += other_value
 		else
-			L1[key] = other_value
+			L1[key] = other_value
\ No newline at end of file
diff --git a/code/__HELPERS/unsorted.dm b/code/__HELPERS/unsorted.dm
index ce294f3749..27b70d28c5 100644
--- a/code/__HELPERS/unsorted.dm
+++ b/code/__HELPERS/unsorted.dm
@@ -451,10 +451,6 @@ Turf and target are separate in case you want to teleport some distance from a t
 	var/y = min(world.maxy, max(1, A.y + dy))
 	return locate(x,y,A.z)
 
-/proc/arctan(x)
-	var/y=arcsin(x/sqrt(1+x*x))
-	return y
-
 /*
 	Gets all contents of contents and returns them all in a list.
 */
diff --git a/tgstation.dme b/tgstation.dme
index 31db79ce1f..a18113d9c9 100755
--- a/tgstation.dme
+++ b/tgstation.dme
@@ -16,6 +16,7 @@
 #include "_maps\_basemap.dm"
 #include "code\_compile_options.dm"
 #include "code\world.dm"
+#include "code\__DEFINES\__513_compatibility.dm"
 #include "code\__DEFINES\_globals.dm"
 #include "code\__DEFINES\_protect.dm"
 #include "code\__DEFINES\_tick.dm"