diff --git a/code/__HELPERS/matrices.dm b/code/__HELPERS/matrices.dm
index a79e0866211..075a5e5ae0e 100644
--- a/code/__HELPERS/matrices.dm
+++ b/code/__HELPERS/matrices.dm
@@ -185,15 +185,24 @@ round(cos_inv_third+sqrt3_sin, 0.001), round(cos_inv_third-sqrt3_sin, 0.001), ro
 			output[offset+x] = round(A[offset+1]*B[x] + A[offset+2]*B[x+4] + A[offset+3]*B[x+8] + A[offset+4]*B[x+12]+(y == 5?B[x+16]:0), 0.001)
 	return output
 
-///Converts RGB shorthands into RGBA matrices complete of constants rows (ergo a 20 keys list in byond).
-/proc/color_to_full_rgba_matrix(color)
+/**
+ * Converts RGB shorthands into RGBA matrices complete of constants rows (ergo a 20 keys list in byond).
+ * if return_identity_on_fail is true, stack_trace is called instead of CRASH, and an identity is returned.
+ */
+/proc/color_to_full_rgba_matrix(color, return_identity_on_fail = TRUE)
+	if(!color)
+		return color_matrix_identity()
 	if(istext(color))
 		var/list/L = ReadRGB(color)
 		if(!L)
-			CRASH("Invalid/unsupported color format argument in color_to_full_rgba_matrix()")
+			var/message = "Invalid/unsupported color ([color]) argument in color_to_full_rgba_matrix()"
+			if(return_identity_on_fail)
+				stack_trace(message)
+				return color_matrix_identity()
+			CRASH(message)
 		return list(L[1]/255,0,0,0, 0,L[2]/255,0,0, 0,0,L[3]/255,0, 0,0,0,L.len>3?L[4]/255:1, 0,0,0,0)
-	else if(!islist(color)) //invalid format
-		return color_matrix_identity()
+	if(!islist(color)) //invalid format
+		CRASH("Invalid/unsupported color ([color]) argument in color_to_full_rgba_matrix()")
 	var/list/L = color
 	switch(L.len)
 		if(3 to 5) // row-by-row hexadecimals
@@ -219,7 +228,11 @@ round(cos_inv_third+sqrt3_sin, 0.001), round(cos_inv_third-sqrt3_sin, 0.001), ro
 				for(var/b in 1 to 20-L.len)
 					. += 0
 		else
-			CRASH("Invalid/unsupported color format argument in color_to_full_rgba_matrix()")
+			var/message = "Invalid/unsupported color (list of length [L.len]) argument in color_to_full_rgba_matrix()"
+			if(return_identity_on_fail)
+				stack_trace(message)
+				return color_matrix_identity()
+			CRASH(message)
 
 #undef LUMA_R
 #undef LUMA_G
diff --git a/code/modules/client/client_colour.dm b/code/modules/client/client_colour.dm
index d45bb8db4fc..88573c78e23 100644
--- a/code/modules/client/client_colour.dm
+++ b/code/modules/client/client_colour.dm
@@ -16,8 +16,8 @@
  * Define subtypes of this datum
  */
 /datum/client_colour
-	///Any client.color-valid value
-	var/colour = ""
+	///The color we want to give to the client. This has to be either a hexadecimal color or a color matrix.
+	var/colour
 	///The mob that owns this client_colour.
 	var/mob/owner
 	/**
@@ -32,8 +32,8 @@
 	///Same as above, but on removal.
 	var/fade_out = 0
 
-/datum/client_colour/New(mob/_owner)
-	owner = _owner
+/datum/client_colour/New(mob/owner)
+	src.owner = owner
 
 /datum/client_colour/Destroy()
 	if(!QDELETED(owner))
@@ -150,7 +150,6 @@
 
 /datum/client_colour/glass_colour
 	priority = PRIORITY_LOW
-	colour = "red"
 
 /datum/client_colour/glass_colour/green
 	colour = "#aaffaa"
@@ -212,9 +211,10 @@
 	colour = list(0,0,0,0,0,0,0,0,0,1,0,0) //pure red.
 	fade_out = 10
 
-/datum/client_colour/bloodlust/New(mob/_owner)
+/datum/client_colour/bloodlust/New(mob/owner)
 	..()
-	addtimer(CALLBACK(src, PROC_REF(update_colour), list(1,0,0,0.8,0.2,0, 0.8,0,0.2,0.1,0,0), 10, SINE_EASING|EASE_OUT), 1)
+	if(owner)
+		addtimer(CALLBACK(src, PROC_REF(update_colour), list(1,0,0,0.8,0.2,0, 0.8,0,0.2,0.1,0,0), 10, SINE_EASING|EASE_OUT), 1)
 
 /datum/client_colour/rave
 	priority = PRIORITY_LOW
diff --git a/code/modules/surgery/organs/internal/heart/_heart.dm b/code/modules/surgery/organs/internal/heart/_heart.dm
index 78c95dadd25..ce4b948c653 100644
--- a/code/modules/surgery/organs/internal/heart/_heart.dm
+++ b/code/modules/surgery/organs/internal/heart/_heart.dm
@@ -194,7 +194,7 @@
 
 /datum/client_colour/cursed_heart_blood
 	priority = 100 //it's an indicator you're dying, so it's very high priority
-	colour = "red"
+	colour = "#FF0000"
 
 /obj/item/organ/internal/heart/cybernetic
 	name = "basic cybernetic heart"
diff --git a/code/modules/unit_tests/_unit_tests.dm b/code/modules/unit_tests/_unit_tests.dm
index 8e99e4bdc97..9cc43e4ce22 100644
--- a/code/modules/unit_tests/_unit_tests.dm
+++ b/code/modules/unit_tests/_unit_tests.dm
@@ -110,6 +110,7 @@
 #include "chain_pull_through_space.dm"
 #include "chat_filter.dm"
 #include "circuit_component_category.dm"
+#include "client_colours.dm"
 #include "closets.dm"
 #include "clothing_under_armor_subtype_check.dm"
 #include "combat.dm"
diff --git a/code/modules/unit_tests/client_colours.dm b/code/modules/unit_tests/client_colours.dm
new file mode 100644
index 00000000000..55b6e0b24ad
--- /dev/null
+++ b/code/modules/unit_tests/client_colours.dm
@@ -0,0 +1,9 @@
+///Checks that client colours have valid colour variables values at least when inited.
+/datum/unit_test/client_colours
+
+/datum/unit_test/client_colours/Run()
+	for(var/datum/client_colour/colour as anything in subtypesof(/datum/client_colour))
+		// colours can be color matrices (lists), which initial() cannot read.
+		colour = new colour
+		if(!color_to_full_rgba_matrix(colour.colour, FALSE))
+			TEST_FAIL("[colour.type] has an invalid default colour value: [colour.colour]")