diff --git a/tl.lua b/tl.lua
index 8ebbcff3..d92997b0 100644
--- a/tl.lua
+++ b/tl.lua
@@ -10091,6 +10091,9 @@ a.types[i], b.types[i]), }
       FACT_TRUTHY = TruthyFact({})
 
       facts_and = function(w, f1, f2)
+         if not f1 and not f2 then
+            return
+         end
          return AndFact({ f1 = f1, f2 = f2, w = w })
       end
 
diff --git a/tl.tl b/tl.tl
index be4ecb9c..cde49da6 100644
--- a/tl.tl
+++ b/tl.tl
@@ -10091,6 +10091,9 @@ do
       FACT_TRUTHY = TruthyFact {}
 
       facts_and = function(w: Where, f1: Fact, f2: Fact): Fact
+         if not f1 and not f2 then
+            return
+         end
          return AndFact { f1 = f1, f2 = f2, w = w }
       end