diff --git a/src/playercards/AllCardsBag.ttslua b/src/playercards/AllCardsBag.ttslua
index e250e22f..5207a8e1 100644
--- a/src/playercards/AllCardsBag.ttslua
+++ b/src/playercards/AllCardsBag.ttslua
@@ -241,8 +241,8 @@ function buildSupplementalIndexes()
           writeToNestedTable(customInvestigatorData, "InvestigatorSubdata", cardId, "cards", cardId)
 
           -- read the signatures
-          if card.metadata.signatures then
-            for sigId, sigCount in pairs(card.metadata.signatures[1]) do
+          if card.metadata.signatures and type(card.metadata.signatures) == "table" then
+            for sigId, sigCount in pairs(card.metadata.signatures[1] or {}) do
               customSignatureDict[sigId] = true
               for i = 1, sigCount do
                 writeToNestedTable(customInvestigatorData, "InvestigatorSubdata", cardId, "signatures", sigId)