diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index 56e88002b..ee6008c2b 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -3885,7 +3885,7 @@ void AActor::Tick ()
 		// (for backwards compatibility this must check for lack of damage function, not for zero damage!)
 		if ((flags & MF_MISSILE) && Vel.X == 0 && Vel.Y == 0 && !IsZeroDamage())
 		{
-			Vel.X = MinVel;
+			VelFromAngle(MinVel);
 		}
 
 		// Handle X and Y velocities
diff --git a/wadsrc/static/zscript/actors/shared/fastprojectile.zs b/wadsrc/static/zscript/actors/shared/fastprojectile.zs
index da0c003e1..befc4252d 100644
--- a/wadsrc/static/zscript/actors/shared/fastprojectile.zs
+++ b/wadsrc/static/zscript/actors/shared/fastprojectile.zs
@@ -87,7 +87,7 @@ class FastProjectile : Actor
 			// force some lateral movement so that collision detection works as intended.
 			if (bMissile && Vel.X == 0 && Vel.Y == 0 && !IsZeroDamage())
 			{
-				Vel.X = MinVel;
+				VelFromAngle(MinVel);
 			}
 
 			Vector3 frac = Vel / count;