diff --git a/hypgraph.cpp b/hypgraph.cpp
index 426d1991..bcb401a4 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -1154,6 +1154,7 @@ void centerpc(ld aspd) {
   DEBBI(DF_GRAPH, ("center pc"));
   
   ors::unrotate(cwtV); ors::unrotate(View);
+  if(invalid_matrix(cwtV)) return;
   
   transmatrix T = cwtV;
   #if MAXMDIM >= 4
diff --git a/shmup.cpp b/shmup.cpp
index 552a2f6c..992c43e9 100644
--- a/shmup.cpp
+++ b/shmup.cpp
@@ -1014,7 +1014,7 @@ void monster::store() {
   }
 
 void monster::findpat() {
-  isVirtual = !gmatrix.count(base);
+  isVirtual = !gmatrix.count(base) || invalid_matrix(gmatrix[base]);
   if(!isVirtual) pat = gmatrix[base] * at;
   else pat = at;
   }
@@ -3546,6 +3546,7 @@ void init() {
       pc[i]->at = Id;
     else
       pc[i]->at = spin(2*M_PI*i/players) * xpush(firstland == laMotion ? .5 : .3) * Id;
+    pc[i]->pat = pc[i]->at;
     pc[i]->base = cwt.at;
     pc[i]->vel = 0;
     pc[i]->inBoat = (firstland == laCaribbean || firstland == laOcean || firstland == laLivefjord ||