diff --git a/polymer/eduke32/build/src/sdlayer.c b/polymer/eduke32/build/src/sdlayer.c
index 1ef1a21e4..b126d9b17 100644
--- a/polymer/eduke32/build/src/sdlayer.c
+++ b/polymer/eduke32/build/src/sdlayer.c
@@ -319,6 +319,7 @@ int32_t initsystem(void)
     }
 
     signal(SIGSEGV, sighandler);
+    signal(SIGILL, sighandler);  /* clang -fcatch-undefined-behavior uses an ill. insn */
     signal(SIGABRT, sighandler);
     signal(SIGFPE, sighandler);
 
diff --git a/polymer/eduke32/source/actors.c b/polymer/eduke32/source/actors.c
index e063160b0..23f9a548b 100644
--- a/polymer/eduke32/source/actors.c
+++ b/polymer/eduke32/source/actors.c
@@ -487,7 +487,8 @@ int32_t block_deletesprite = 0;
 #ifdef POLYMER
 static void A_DeletePolymerLight(int32_t s)
 {
-    polymer_deletelight(actor[s].lightId);
+    if (actor[s].lightId >= 0)
+        polymer_deletelight(actor[s].lightId);
     actor[s].lightId = -1;
     actor[s].lightptr = NULL;
 }
diff --git a/polymer/eduke32/source/astub.c b/polymer/eduke32/source/astub.c
index 1a1093c9e..e69ba2402 100644
--- a/polymer/eduke32/source/astub.c
+++ b/polymer/eduke32/source/astub.c
@@ -315,6 +315,7 @@ static void DeletePolymerLights(void)
         if (spritelightptr[i] != NULL)
         {
             polymer_deletelight(spritelightid[i]);
+            spritelightid[i] = -1;
             spritelightptr[i] = NULL;
         }
 }