Enabling patch.dta, and also upping the number of SPR2_ slots (not just freeslots) to be equivalent to FF_FRAMEMASK.

src/doomdef.h

@@ -158,7 +158,7 @@ extern FILE *logstream;
 
 // Does this version require an added patch file?
 // Comment or uncomment this as necessary.
-//#define USE_PATCH_DTA
+#define USE_PATCH_DTA
 
 // Modification options
 // If you want to take advantage of the Master Server's ability to force clients to update

src/info.h

@@ -632,7 +632,7 @@ enum playersprite
 	SPR2_SFLT,
 
 	SPR2_FIRSTFREESLOT,
-	SPR2_LASTFREESLOT = SPR2_FIRSTFREESLOT + NUMSPRITEFREESLOTS - 1,
+	SPR2_LASTFREESLOT = 0x1ff, // FF_FRAMEMASK (cannot use #define'd constants as enum value...) - previously set to SPR2_FIRSTFREESLOT + NUMSPRITEFREESLOTS - 1,
 	NUMPLAYERSPRITES
 };