diff --git a/ref-verification/hash.saw b/ref-verification/hash.saw
index d3d1a64..97b9c20 100644
--- a/ref-verification/hash.saw
+++ b/ref-verification/hash.saw
@@ -4,12 +4,25 @@ include "common.saw";
 
 thm_P12 <- mk_P12;
 
-thm_hash <- llvm_verify
+let ss0 = cryptol_ss ();
+
+thm_unfold_iv <- prove_print rme
+  (rewrite ss0
+    {{ Ascon_p`{12} [Hash256_IV, 0, 0, 0, 0]
+       ==
+       [0x9b1e5494e934d681,
+        0x4bc3a01e333751d2,
+        0xae65396c6b34b81a,
+        0x3c7fd4a4d56a4db3,
+        0x1a5c464906c5976d]
+    }});
+
+let verify_hash256 IN_len =
+  llvm_verify
   m "crypto_hash"
   [thm_P12]
   true
   do {
-    let IN_len = 17;
     let IN_type = llvm_array IN_len (llvm_int 8);
     (IN, IN_ptr) <- fresh_alloc_readonly "IN" IN_type;
 
@@ -19,6 +32,28 @@ thm_hash <- llvm_verify
     llvm_execute_func [OUT_ptr, IN_ptr, llvm_term {{ `IN_len:[64] }}];
 
     llvm_points_to OUT_ptr (llvm_term {{ Hash256_bytes IN }});
-    llvm_return (llvm_term {{ 0 : [32] }});
-  }
-  abc;
+      llvm_return (llvm_term {{ 0 : [32] }});
+    };
+    
+// What4 will have completely evaluated the term from symbolic evaluation
+// so don't try to keep Ascon_p uninterpreted at all.
+verify_hash256 0 rme;
+
+for [      1,  2,  3,  4,  5,  6,  7,
+       8,  9, 10, 11, 12, 13, 14, 15,
+      16, 17, 18, 19, 20, 21, 22, 23,
+      24, 25, 26, 27, 28, 29, 30, 31,
+      32, 33] (\IN_len -> do {
+  
+  print ("Verifying for size", IN_len);
+  verify_hash256 IN_len
+  do { 
+      // What4 will have simplified away the application of
+      // Ascon_p to the IV, so simplify that away before
+      // holding all other Ascon_p occurences uninterpreted.
+
+      unfolding ["Hash256_bytes", "Hash256", "hashBlocks"];
+      simplify (addsimp thm_unfold_iv ss0);
+      w4_unint_rme ["Ascon_p"];
+    };
+});