diff --git a/pkg/base/obj_nade.lua b/pkg/base/obj_nade.lua
index 6083b5f..ea9d68d 100644
--- a/pkg/base/obj_nade.lua
+++ b/pkg/base/obj_nade.lua
@@ -99,7 +99,7 @@ function new_nade(settings)
 			this.vz = this.vz * MODE_NADE_ADAMP
 		end
 
-		this.vy = this.vy + 5*9.81*MODE_NADE_STEP*MODE_NADE_STEP
+		this.vy = this.vy + 5*MODE_GRAVITY*MODE_NADE_STEP*MODE_NADE_STEP
 	end
 
 	function this.explode_dmg()
diff --git a/pkg/base/obj_particle.lua b/pkg/base/obj_particle.lua
index 96320e9..b32ae56 100644
--- a/pkg/base/obj_particle.lua
+++ b/pkg/base/obj_particle.lua
@@ -139,7 +139,7 @@ function new_particle(settings)
 			this.vz = this.vz * this.adamp
 		end
 		
-		this.vy = this.vy + 5*9.81*this.step*this.step
+		this.vy = this.vy + 5*MODE_GRAVITY*this.step*this.step
 	end
 	
 	function this.tick(sec_current, sec_delta)
diff --git a/pkg/iceball/lib/wobj.lua b/pkg/iceball/lib/wobj.lua
index a6d7c86..7b4482e 100644
--- a/pkg/iceball/lib/wobj.lua
+++ b/pkg/iceball/lib/wobj.lua
@@ -46,7 +46,7 @@ function wobj_new(settings)
 	-- Calculate jump speed required to jump d blocks high.
 	function this.get_jump_speed(d)
 		local grav = this.grav or 1.0
-		local acc = 9.81*4.0*grav
+		local acc = MODE_GRAVITY*4.0*grav
 
 		-- d = a*t*t/2
 		-- d, a known; find t
@@ -96,7 +96,7 @@ function wobj_new(settings)
 		-- d = v*t + (a*t*t)/2
 		-- Tested to be consistent over a wide variety of sec_delta values.
 		if this.grav then
-			local acc = 9.81*4.0*this.grav
+			local acc = MODE_GRAVITY*4.0*this.grav
 			this.vg.y = this.vg.y + sec_delta*acc
 		end