diff --git a/src/game/game_176d70.c b/src/game/game_176d70.c
index afd8c3024..51957d9bb 100644
--- a/src/game/game_176d70.c
+++ b/src/game/game_176d70.c
@@ -7099,7 +7099,7 @@ s32 menuhandlerMpSimulantSlot(u32 operation, struct menu_item *item, s32 *value)
 	case MENUOP_SET:
 		g_MenuStack[g_MpPlayerNum].slotindex = item->param;
 
-		if ((g_MpSetup.simslots & (1 << (item->param + 4))) == 0) {
+		if ((g_MpSetup.chrslots & (1 << (item->param + 4))) == 0) {
 			menuPushDialog(&g_MpAddSimulantMenuDialog);
 		} else if (var80090af0 == 1) {
 			menuPushDialog(&menudialog_1b414);
diff --git a/src/game/game_1999b0.c b/src/game/game_1999b0.c
index b1845f2d8..a5b3ed9fe 100644
--- a/src/game/game_1999b0.c
+++ b/src/game/game_1999b0.c
@@ -2155,6 +2155,46 @@ glabel func0f19b540
 /*  f19b660:	00000000 */ 	sll	$zero,$zero,0x0
 );
 
+// Mismatch because it's doing something weird with the chrslots, and also
+// writing to negative mpsim offsets. This code below might not be functionally
+// identical.
+//void func0f19b540(void)
+//{
+//	if (var800acc10 == 5) {
+//		s32 slot = 0;
+//		s32 i;
+//		u32 *ptr;
+//
+//		for (i = 0; i < 4; i++) {
+//			if (g_MpSetup.chrslots & (1 << i)) {
+//				g_MpChrs[i].unk9d = 0x80;
+//				slot++;
+//			}
+//		}
+//
+//		g_MpSetup.chrslots &= 0x000f;
+//		ptr = &var800ac798[slot];
+//
+//		for (i = 0; i != 8; i++) {
+//			g_MpSimulants[i].unk48 = *(ptr - 1);
+//
+//			if (*(ptr - 1) != 6) {
+//				g_MpSetup.chrslots |= 1 << (i + 4);
+//			}
+//
+//			ptr++;
+//		}
+//
+//		if (g_MpSetup.scenario == MPSCENARIO_KINGOFTHEHILL) {
+//			g_Vars.mphilltime = 10;
+//		}
+//	} else {
+//		if (!mpIsChallengeComplete(CHALLENGE_UNK64)) {
+//			g_MpSetup.chrslots &= 0x00ff;
+//		}
+//	}
+//}
+
 s32 mpGetNumAvailableChallenges(void)
 {
 	s32 challengeindex;
diff --git a/src/gvars/gvars.c b/src/gvars/gvars.c
index 68a1e1a32..ca1655f96 100644
--- a/src/gvars/gvars.c
+++ b/src/gvars/gvars.c
@@ -30637,14 +30637,7 @@ u32 var800ac52c = 0;
 u32 var800ac530 = 0;
 u32 var800ac534 = 0;
 struct mpsim g_MpSimulants[8] = {0};
-u32 var800ac798 = 0;
-u32 var800ac79c = 0;
-u32 var800ac7a0 = 0;
-u32 var800ac7a4 = 0;
-u32 var800ac7a8 = 0;
-u32 var800ac7ac = 0;
-u32 var800ac7b0 = 0;
-u32 var800ac7b4 = 0;
+u32 var800ac798[8] = {0};
 struct mpchr g_MpChrs[4] = {0};
 u32 var800aca38 = 0;
 u32 var800aca3c = 0;
diff --git a/src/include/game/game_1999b0.h b/src/include/game/game_1999b0.h
index aa52142b6..cdfb49948 100644
--- a/src/include/game/game_1999b0.h
+++ b/src/include/game/game_1999b0.h
@@ -27,7 +27,7 @@ u32 func0f19ab70(void);
 u32 func0f19af3c(void);
 bool mpIsChallengeAvailable(s32 challengeindex);
 void func0f19afdc(void);
-u32 func0f19b540(void);
+void func0f19b540(void);
 s32 mpGetNumAvailableChallenges(void);
 char *mpChallengeGetName(s32 challengeindex);
 u32 func0f19b6f8(void);
diff --git a/src/include/gvars/gvars.h b/src/include/gvars/gvars.h
index 0aa3520e1..cc9a6c419 100644
--- a/src/include/gvars/gvars.h
+++ b/src/include/gvars/gvars.h
@@ -844,7 +844,7 @@ extern u32 var800ac4d0;
 extern u32 var800ac500;
 extern u32 var800ac530;
 extern struct mpsim g_MpSimulants[8];
-extern u32 var800ac798;
+extern u32 var800ac798[8];
 extern struct mpchr g_MpChrs[];
 extern u32 var800aca38;
 extern u32 var800acad8;
diff --git a/src/include/types.h b/src/include/types.h
index 2f4c91e7f..136f7cf53 100644
--- a/src/include/types.h
+++ b/src/include/types.h
@@ -3998,7 +3998,7 @@ struct mpchr {
 	/*0x94*/ u8 unk94;
 	/*0x95*/ u8 title;
 	/*0x98*/ u32 unk98;
-	/*0x9c*/ u32 unk9c;
+	/*0x9c*/ u8 unk9c;
 };
 
 struct missionconfig {
@@ -4029,7 +4029,16 @@ struct mpsetup {
 	/*0x8009cb9a*/ u8 timelimit;
 	/*0x8009cb9b*/ u8 scorelimit;
 	/*0x8009cb9c*/ u16 teamscorelimit;
-	/*0x8009cb9e*/ u16 simslots;
+
+	/**
+	 * Each bit signifies that a player or sim is participating.
+	 *
+	 * Bits 0x000f are for players
+	 * Bits 0x0ff0 are for sims
+	 * Bits 0xf000 are probably not used
+	 */
+	/*0x8009cb9e*/ u16 chrslots;
+
 	/*0x8009cba0*/ u32 unk18;
 	/*0x8009cba4*/ u32 unk1c;
 	/*0x8009cba8*/ bool saved;
@@ -4085,7 +4094,7 @@ struct mpsim {
 	/*0x3c*/ u32 unk3c;
 	/*0x40*/ u32 unk40;
 	/*0x44*/ u32 unk44;
-	/*0x48*/ u32 unk48;
+	/*0x48*/ u8 unk48;
 };
 
 struct savelocation {