diff --git a/source/duke3d/src/actors.cpp b/source/duke3d/src/actors.cpp
index 84b7830ce..27f86280a 100644
--- a/source/duke3d/src/actors.cpp
+++ b/source/duke3d/src/actors.cpp
@@ -4682,7 +4682,7 @@ ACTOR_STATIC void G_MoveActors(void)
                 if (pData[3] > 280)
                 {
                     pSprite->pal = 0;
-                    pData[0] = 0;
+                    pData[0] = pData[3] = 0;
                     goto next_sprite;
                 }
                 A_Fall(spriteNum);
@@ -4783,6 +4783,8 @@ ACTOR_STATIC void G_MoveActors(void)
                 {
                     static const char slimeFrames[] = { 5, 5, 6, 6, 7, 7, 6, 5 };
 
+                    Bassert(pData[3] < ARRAY_SSIZE(slimeFrames));
+
                     pSprite->picnum = GREENSLIME + slimeFrames[pData[3]];
 
                     if (pData[3] == 5)