diff --git a/src/d_player.h b/src/d_player.h
index 892adeebf..75ed533d9 100644
--- a/src/d_player.h
+++ b/src/d_player.h
@@ -141,6 +141,7 @@ public:
 	FNameNoInit	MorphWeapon;
 	fixed_t		AttackZOffset;			// attack height, relative to player center
 	fixed_t		UseRange;				// [NS] Distance at which player can +use
+	fixed_t		AirCapacity;			// Multiplier for air supply underwater.
 	const PClass *FlechetteType;
 
 	// [CW] Fades for when you are being damaged.
diff --git a/src/p_user.cpp b/src/p_user.cpp
index c427353a5..e2c8b80c9 100644
--- a/src/p_user.cpp
+++ b/src/p_user.cpp
@@ -477,6 +477,10 @@ void APlayerPawn::Serialize (FArchive &arc)
 	{
 		arc << UseRange;
 	}
+	if (SaveVersion >= 4503)
+	{
+		arc << AirCapacity;
+	}
 }
 
 //===========================================================================
@@ -1066,7 +1070,7 @@ bool APlayerPawn::ResetAirSupply (bool playgasp)
 	{
 		S_Sound (this, CHAN_VOICE, "*gasp", 1, ATTN_NORM);
 	}
-	if (level.airsupply> 0) player->air_finished = level.time + level.airsupply;
+	if (level.airsupply> 0 && player->mo->AirCapacity > 0) player->air_finished = level.time + FixedMul(level.airsupply, player->mo->AirCapacity);
 	else player->air_finished = INT_MAX;
 	return wasdrowning;
 }
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index 61a18b370..fcb3bc2ef 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -2419,6 +2419,15 @@ DEFINE_CLASS_PROPERTY_PREFIX(player, userange, F, PlayerPawn)
 	defaults->UseRange = z;
 }
 
+//==========================================================================
+//
+//==========================================================================
+DEFINE_CLASS_PROPERTY_PREFIX(player, aircapacity, F, PlayerPawn)
+{
+	PROP_FIXED_PARM(z, 0);
+	defaults->AirCapacity = z;
+}
+
 //==========================================================================
 //
 //==========================================================================
diff --git a/src/version.h b/src/version.h
index 8bdd8ca81..01fbc7a88 100644
--- a/src/version.h
+++ b/src/version.h
@@ -76,7 +76,7 @@ const char *GetVersionString();
 
 // Use 4500 as the base git save version, since it's higher than the
 // SVN revision ever got.
-#define SAVEVER 4502
+#define SAVEVER 4503
 
 #define SAVEVERSTRINGIFY2(x) #x
 #define SAVEVERSTRINGIFY(x) SAVEVERSTRINGIFY2(x)
diff --git a/wadsrc/static/actors/shared/player.txt b/wadsrc/static/actors/shared/player.txt
index 5457880a7..159d4cca9 100644
--- a/wadsrc/static/actors/shared/player.txt
+++ b/wadsrc/static/actors/shared/player.txt
@@ -32,6 +32,7 @@ Actor PlayerPawn : Actor native
 	Player.DamageScreenColor "ff 00 00"
 	Player.MugShotMaxHealth 0
 	Player.FlechetteType "ArtiPoisonBag3"
+	Player.AirCapacity 1
 	Obituary "$OB_MPDEFAULT"
 }