diff --git a/unison-runtime/package.yaml b/unison-runtime/package.yaml
index e9221c6d3e..850a83046c 100644
--- a/unison-runtime/package.yaml
+++ b/unison-runtime/package.yaml
@@ -11,13 +11,17 @@ flags:
   stackchecks:
     manual: true
     default: false
+  dumpcore:
+    manual: true
+    default: false
 
 when:
   - condition: flag(arraychecks)
     cpp-options: -DARRAY_CHECK
   - condition: flag(stackchecks)
     cpp-options: -DSTACK_CHECK
-
+  - condition: flag(dumpcore)
+    ghc-options: -ddump-simpl -ddump-stg-final -ddump-to-file -dsuppress-coercions -dsuppress-idinfo -dsuppress-module-prefixes # -dsuppress-type-applications -dsuppress-type-signatures
 
 library:
   source-dirs: src
diff --git a/unison-runtime/src/Unison/Runtime/Machine.hs b/unison-runtime/src/Unison/Runtime/Machine.hs
index 1143d579fa..e0bac70278 100644
--- a/unison-runtime/src/Unison/Runtime/Machine.hs
+++ b/unison-runtime/src/Unison/Runtime/Machine.hs
@@ -1244,7 +1244,7 @@ uprim1 !stk NOTB !i = do
   pure stk
 {-# INLINE uprim1 #-}
 
-uprim2 :: (HasCallStack) => Stack -> UPrim2 -> Int -> Int -> IO Stack
+uprim2 :: Stack -> UPrim2 -> Int -> Int -> IO Stack
 uprim2 !stk ADDI !i !j = do
   m <- upeekOff stk i
   n <- upeekOff stk j
diff --git a/unison-runtime/unison-runtime.cabal b/unison-runtime/unison-runtime.cabal
index cc6e59bc6a..a23132a3f9 100644
--- a/unison-runtime/unison-runtime.cabal
+++ b/unison-runtime/unison-runtime.cabal
@@ -21,6 +21,10 @@ flag arraychecks
   manual: True
   default: False
 
+flag dumpcore
+  manual: True
+  default: False
+
 flag stackchecks
   manual: True
   default: False
@@ -142,6 +146,8 @@ library
     cpp-options: -DARRAY_CHECK
   if flag(stackchecks)
     cpp-options: -DSTACK_CHECK
+  if flag(dumpcore)
+    ghc-options: -ddump-simpl -ddump-stg-final -ddump-to-file -dsuppress-coercions -dsuppress-idinfo -dsuppress-module-prefixes
 
 test-suite runtime-tests
   type: exitcode-stdio-1.0
@@ -221,3 +227,5 @@ test-suite runtime-tests
     cpp-options: -DARRAY_CHECK
   if flag(stackchecks)
     cpp-options: -DSTACK_CHECK
+  if flag(dumpcore)
+    ghc-options: -ddump-simpl -ddump-stg-final -ddump-to-file -dsuppress-coercions -dsuppress-idinfo -dsuppress-module-prefixes