diff --git a/clash-lib/src/Clash/Backend/SystemVerilog.hs b/clash-lib/src/Clash/Backend/SystemVerilog.hs
index 88928dc138..f9af26948f 100644
--- a/clash-lib/src/Clash/Backend/SystemVerilog.hs
+++ b/clash-lib/src/Clash/Backend/SystemVerilog.hs
@@ -1228,7 +1228,9 @@ expr_ _ (BlackBoxE pNm _ _ _ _ bbCtx _)
 expr_ _ (BlackBoxE pNm _ _ _ _ bbCtx _)
   | pNm == "Clash.Sized.Internal.Index.fromInteger#"
   , [Literal _ (NumLit n), Literal _ i] <- extractLiterals bbCtx
-  = exprLitSV (Just (Index (fromInteger n),fromInteger n)) i
+  , Just k <- clogBase 2 n
+  , let k' = max 1 k
+  = exprLitSV (Just (Index (fromInteger n),k')) i
 
 expr_ b (BlackBoxE _ libs imps inc bs bbCtx b') =
   parenIf (b || b') (Ap (renderBlackBox libs imps inc bs bbCtx <*> pure 0))
diff --git a/clash-lib/src/Clash/Backend/Verilog.hs b/clash-lib/src/Clash/Backend/Verilog.hs
index 1dd81118db..79884623f0 100644
--- a/clash-lib/src/Clash/Backend/Verilog.hs
+++ b/clash-lib/src/Clash/Backend/Verilog.hs
@@ -1151,7 +1151,9 @@ expr_ _ (BlackBoxE pNm _ _ _ _ bbCtx _)
 expr_ _ (BlackBoxE pNm _ _ _ _ bbCtx _)
   | pNm == "Clash.Sized.Internal.Index.fromInteger#"
   , [Literal _ (NumLit n), Literal _ i] <- extractLiterals bbCtx
-  = exprLit undefValue (Just (Index (fromInteger n),fromInteger n)) i
+  , Just k <- clogBase 2 n
+  , let k' = max 1 k
+  = exprLit undefValue (Just (Index (fromInteger n),k')) i
 
 expr_ b (BlackBoxE _ libs imps inc bs bbCtx b') = do
   parenIf (b || b') (Ap (renderBlackBox libs imps inc bs bbCtx <*> pure 0))