Init the done variable to false

src/mhitm.c

@@ -865,6 +865,7 @@ int dieroll;
     mhm.permdmg = 0;
     mhm.specialdmg = 0;
     mhm.dieroll = dieroll;
+    mhm.done = FALSE;
 
     if ((touch_petrifies(pd) /* or flesh_petrifies() */
          || (mattk->adtyp == AD_DGST && pd == &mons[PM_MEDUSA]))

src/mhitu.c

@@ -972,6 +972,7 @@ register struct attack *mattk;
     mhm.hitflags = MM_MISS;
     mhm.permdmg = 0;
     mhm.specialdmg = 0;
+    mhm.done = FALSE;
 
     if (!canspotmon(mtmp))
         map_invisible(mtmp->mx, mtmp->my);

src/uhitm.c

@@ -4185,6 +4185,7 @@ int specialdmg; /* blessed and/or silver bonus against various things */
     mhm.hitflags = MM_MISS;
     mhm.permdmg = 0;
     mhm.specialdmg = specialdmg;
+    mhm.done = FALSE;
 
     armpro = magic_negation(mdef);
     /* since hero can't be cancelled, only defender's armor applies */