diff --git a/code/game/gamemodes/dynamic/dynamic_rulesets.dm b/code/game/gamemodes/dynamic/dynamic_rulesets.dm
index dda888e1e60..2e0a25f09dc 100644
--- a/code/game/gamemodes/dynamic/dynamic_rulesets.dm
+++ b/code/game/gamemodes/dynamic/dynamic_rulesets.dm
@@ -164,11 +164,11 @@
 			candidates.Remove(P)
 			continue
 		if(antag_flag_override)
-			if(!antag_flag_override in P.client.prefs.be_special || is_banned_from(P.ckey, list(antag_flag_override, ROLE_SYNDICATE)))
+			if(!(antag_flag_override in P.client.prefs.be_special) || is_banned_from(P.ckey, list(antag_flag_override, ROLE_SYNDICATE)))
 				candidates.Remove(P)
 				continue
 		else
-			if(!antag_flag in P.client.prefs.be_special || is_banned_from(P.ckey, list(antag_flag, ROLE_SYNDICATE)))
+			if(!(antag_flag in P.client.prefs.be_special) || is_banned_from(P.ckey, list(antag_flag, ROLE_SYNDICATE)))
 				candidates.Remove(P)
 				continue
 
diff --git a/code/game/gamemodes/dynamic/dynamic_rulesets_latejoin.dm b/code/game/gamemodes/dynamic/dynamic_rulesets_latejoin.dm
index 1340573e6c8..eda3d3ebfcc 100644
--- a/code/game/gamemodes/dynamic/dynamic_rulesets_latejoin.dm
+++ b/code/game/gamemodes/dynamic/dynamic_rulesets_latejoin.dm
@@ -17,7 +17,7 @@
 				candidates.Remove(P)
 				continue
 		else 
-			if(!antag_flag in P.client.prefs.be_special || is_banned_from(P.ckey, list(antag_flag, ROLE_SYNDICATE)))
+			if(!(antag_flag in P.client.prefs.be_special) || is_banned_from(P.ckey, list(antag_flag, ROLE_SYNDICATE)))
 				candidates.Remove(P)
 				continue
 		if (P.mind.assigned_role in restricted_roles) // Does their job allow for it?
diff --git a/code/game/gamemodes/dynamic/dynamic_rulesets_midround.dm b/code/game/gamemodes/dynamic/dynamic_rulesets_midround.dm
index a6878f0fb2c..9e4a82a1a8f 100644
--- a/code/game/gamemodes/dynamic/dynamic_rulesets_midround.dm
+++ b/code/game/gamemodes/dynamic/dynamic_rulesets_midround.dm
@@ -44,7 +44,7 @@
 				candidates.Remove(M)
 				continue
 		else
-			if(!antag_flag in M.client.prefs.be_special || is_banned_from(M.ckey, list(antag_flag, ROLE_SYNDICATE)))
+			if(!(antag_flag in M.client.prefs.be_special) || is_banned_from(M.ckey, list(antag_flag, ROLE_SYNDICATE)))
 				candidates.Remove(M)
 				continue
 		if (M.mind)
diff --git a/code/game/objects/items/eightball.dm b/code/game/objects/items/eightball.dm
index 34ef16e164c..3e83fe87c1c 100644
--- a/code/game/objects/items/eightball.dm
+++ b/code/game/objects/items/eightball.dm
@@ -206,7 +206,7 @@
 	switch(action)
 		if("vote")
 			var/selected_answer = params["answer"]
-			if(!selected_answer in possible_answers)
+			if(!(selected_answer in possible_answers))
 				return
 			else
 				votes[user.ckey] = selected_answer
diff --git a/code/game/objects/items/pet_carrier.dm b/code/game/objects/items/pet_carrier.dm
index b4cce95b6bb..464721cec1f 100644
--- a/code/game/objects/items/pet_carrier.dm
+++ b/code/game/objects/items/pet_carrier.dm
@@ -122,7 +122,7 @@
 	if(user.mob_size <= MOB_SIZE_SMALL)
 		to_chat(user, "<span class='notice'>You poke a limb through [src]'s bars and start fumbling for the lock switch... (This will take some time.)</span>")
 		to_chat(loc, "<span class='warning'>You see [user] reach through the bars and fumble for the lock switch!</span>")
-		if(!do_after(user, rand(300, 400), target = user) || open || !locked || !user in occupants)
+		if(!do_after(user, rand(300, 400), target = user) || open || !locked || !(user in occupants))
 			return
 		loc.visible_message("<span class='warning'>[user] flips the lock switch on [src] by reaching through!</span>", null, null, null, user)
 		to_chat(user, "<span class='boldannounce'>Bingo! The lock pops open!</span>")
@@ -132,7 +132,7 @@
 	else
 		loc.visible_message("<span class='warning'>[src] starts rattling as something pushes against the door!</span>", null, null, null, user)
 		to_chat(user, "<span class='notice'>You start pushing out of [src]... (This will take about 20 seconds.)</span>")
-		if(!do_after(user, 200, target = user) || open || !locked || !user in occupants)
+		if(!do_after(user, 200, target = user) || open || !locked || !(user in occupants))
 			return
 		loc.visible_message("<span class='warning'>[user] shoves out of	[src]!</span>", null, null, null, user)
 		to_chat(user, "<span class='notice'>You shove open [src]'s door against the lock's resistance and fall out!</span>")
@@ -185,7 +185,7 @@
 	occupant_weight += occupant.mob_size
 
 /obj/item/pet_carrier/proc/remove_occupant(mob/living/occupant, turf/new_turf)
-	if(!occupant in occupants || !istype(occupant))
+	if(!(occupant in occupants) || !istype(occupant))
 		return
 	occupant.forceMove(new_turf ? new_turf : drop_location())
 	occupants -= occupant
diff --git a/code/modules/admin/view_variables/modify_variables.dm b/code/modules/admin/view_variables/modify_variables.dm
index aea991ae390..fd88f7f88ab 100644
--- a/code/modules/admin/view_variables/modify_variables.dm
+++ b/code/modules/admin/view_variables/modify_variables.dm
@@ -295,7 +295,7 @@ GLOBAL_PROTECT(VVpixelmovement)
 	var/var_value
 
 	if(param_var_name)
-		if(!param_var_name in O.vars)
+		if(!(param_var_name in O.vars))
 			to_chat(src, "A variable with this name ([param_var_name]) doesn't exist in this datum ([O])")
 			return
 		variable = param_var_name
diff --git a/code/modules/antagonists/clockcult/clock_structures/heralds_beacon.dm b/code/modules/antagonists/clockcult/clock_structures/heralds_beacon.dm
index a1e5f575b0d..cce5c5fa59c 100644
--- a/code/modules/antagonists/clockcult/clock_structures/heralds_beacon.dm
+++ b/code/modules/antagonists/clockcult/clock_structures/heralds_beacon.dm
@@ -78,7 +78,7 @@
 			return
 		voters += user.key
 	else
-		if(!user.key in voters)
+		if(!(user.key in voters))
 			return
 		voters -= user.key
 	var/votes_left = votes_needed - voters.len