diff --git a/mldsa/src/native/api.h b/mldsa/src/native/api.h
index e210ff2a4..0f1fdeb16 100644
--- a/mldsa/src/native/api.h
+++ b/mldsa/src/native/api.h
@@ -122,7 +122,16 @@ set if there are native implementations for NTT and INTT."
  * Arguments:   - int32_t p[MLDSA_N]: pointer to in/output polynomial
  *
  **************************************************/
-static MLD_INLINE void mld_poly_permute_bitrev_to_custom(int32_t p[MLDSA_N]);
+static MLD_INLINE void mld_poly_permute_bitrev_to_custom(int32_t p[MLDSA_N])
+__contract__(
+  /* We don't specify that this should be a permutation, but only
+   * that it does not change the bound established at the end of
+   * mld_polyvec_matrix_expand.
+   */
+  requires(memory_no_alias(p, sizeof(int32_t) * MLDSA_N))
+  requires(array_bound(p, 0, MLDSA_N, 0, MLDSA_Q))
+  assigns(memory_slice(p, sizeof(int32_t) * MLDSA_N))
+  ensures(array_bound(p, 0, MLDSA_N, 0, MLDSA_Q)));
 #endif /* MLD_USE_NATIVE_NTT_CUSTOM_ORDER */
 
 
diff --git a/mldsa/src/polyvec.c b/mldsa/src/polyvec.c
index 95f7677f6..f6cc08386 100644
--- a/mldsa/src/polyvec.c
+++ b/mldsa/src/polyvec.c
@@ -25,6 +25,8 @@
  * with native backends, which are currently not yet namespaced. */
 #define mld_polymat_permute_bitrev_to_custom \
   MLD_ADD_PARAM_SET(mld_polymat_permute_bitrev_to_custom)
+#define mld_polyvecl_permute_bitrev_to_custom \
+  MLD_ADD_PARAM_SET(mld_polyvecl_permute_bitrev_to_custom)
 #define mld_polyvecl_pointwise_acc_montgomery_c \
   MLD_ADD_PARAM_SET(mld_polyvecl_pointwise_acc_montgomery_c)
 
@@ -34,6 +36,37 @@
  * of coefficients.
  * No-op unless a native backend with a custom ordering is used.
  */
+
+static void mld_polyvecl_permute_bitrev_to_custom(mld_polyvecl *v)
+__contract__(
+  /* We don't specify that this should be a permutation, but only
+   * that it does not change the bound established at the end of
+   * mld_polyvec_matrix_expand. 
+   */
+  requires(memory_no_alias(v, sizeof(mld_polyvecl)))
+  requires(forall(x, 0, MLDSA_L,
+    array_bound(v->vec[x].coeffs, 0, MLDSA_N, 0, MLDSA_Q)))
+  assigns(memory_slice(v, sizeof(mld_polyvecl)))
+  ensures(forall(x, 0, MLDSA_L,
+    array_bound(v->vec[x].coeffs, 0, MLDSA_N, 0, MLDSA_Q))))
+{
+#if defined(MLD_USE_NATIVE_NTT_CUSTOM_ORDER)
+  unsigned i;
+  for (i = 0; i < MLDSA_L; i++)
+  __loop__(
+     assigns(i, memory_slice(v, sizeof(mld_polyvecl)))
+     invariant(i <= MLDSA_L)
+     invariant(forall(x, 0, MLDSA_L,
+       array_bound(v->vec[x].coeffs, 0, MLDSA_N, 0, MLDSA_Q))))
+  {
+    mld_poly_permute_bitrev_to_custom(v->vec[i].coeffs);
+  }
+#else  /* MLD_USE_NATIVE_NTT_CUSTOM_ORDER */
+  /* Nothing to do */
+  (void)v;
+#endif /* !MLD_USE_NATIVE_NTT_CUSTOM_ORDER */
+}
+
 static void mld_polymat_permute_bitrev_to_custom(mld_polymat *mat)
 __contract__(
   /* We don't specify that this should be a permutation, but only
@@ -48,23 +81,16 @@ __contract__(
     array_bound(mat->vec[k1].vec[l1].coeffs, 0, MLDSA_N, 0, MLDSA_Q))))
 )
 {
-#if defined(MLD_USE_NATIVE_NTT_CUSTOM_ORDER)
-  /* TODO: proof */
-  unsigned int i, j;
+  unsigned int i;
   for (i = 0; i < MLDSA_K; i++)
+  __loop__(
+    assigns(i, memory_slice(mat, sizeof(mld_polymat)))
+    invariant(i <= MLDSA_K)
+    invariant(forall(k1, 0, MLDSA_K, forall(l1, 0, MLDSA_L,
+      array_bound(mat->vec[k1].vec[l1].coeffs, 0, MLDSA_N, 0, MLDSA_Q)))))
   {
-    for (j = 0; j < MLDSA_L; j++)
-    {
-      mld_poly_permute_bitrev_to_custom(mat->vec[i].vec[j].coeffs);
-    }
+    mld_polyvecl_permute_bitrev_to_custom(&mat->vec[i]);
   }
-
-#else /* MLD_USE_NATIVE_NTT_CUSTOM_ORDER */
-
-  /* Nothing to do */
-  ((void)mat);
-
-#endif /* !MLD_USE_NATIVE_NTT_CUSTOM_ORDER */
 }
 #endif /* !MLD_CONFIG_REDUCE_RAM */
 
@@ -925,4 +951,5 @@ void mld_polyveck_unpack_t0(mld_polyveck *p,
 /* To facilitate single-compilation-unit (SCU) builds, undefine all macros.
  * Don't modify by hand -- this is auto-generated by scripts/autogen. */
 #undef mld_polymat_permute_bitrev_to_custom
+#undef mld_polyvecl_permute_bitrev_to_custom
 #undef mld_polyvecl_pointwise_acc_montgomery_c
diff --git a/proofs/cbmc/dummy_backend.h b/proofs/cbmc/dummy_backend.h
index 92a11b566..0fff57564 100644
--- a/proofs/cbmc/dummy_backend.h
+++ b/proofs/cbmc/dummy_backend.h
@@ -24,6 +24,7 @@
 #define MLD_USE_NATIVE_POLYVECL_POINTWISE_ACC_MONTGOMERY_L4
 #define MLD_USE_NATIVE_POLYVECL_POINTWISE_ACC_MONTGOMERY_L5
 #define MLD_USE_NATIVE_POLYVECL_POINTWISE_ACC_MONTGOMERY_L7
+#define MLD_USE_NATIVE_NTT_CUSTOM_ORDER
 
 #include "../../mldsa/src/native/api.h"
 
diff --git a/proofs/cbmc/polymat_permute_bitrev_to_custom/Makefile b/proofs/cbmc/polymat_permute_bitrev_to_custom/Makefile
index 59a2fb467..690eef038 100644
--- a/proofs/cbmc/polymat_permute_bitrev_to_custom/Makefile
+++ b/proofs/cbmc/polymat_permute_bitrev_to_custom/Makefile
@@ -20,7 +20,7 @@ PROOF_SOURCES += $(PROOFDIR)/$(HARNESS_FILE).c
 PROJECT_SOURCES += $(SRCDIR)/mldsa/src/polyvec.c
 
 CHECK_FUNCTION_CONTRACTS=mld_polymat_permute_bitrev_to_custom
-USE_FUNCTION_CONTRACTS=
+USE_FUNCTION_CONTRACTS=mld_polyvecl_permute_bitrev_to_custom
 APPLY_LOOP_CONTRACTS=on
 USE_DYNAMIC_FRAMES=1
 
diff --git a/proofs/cbmc/polyvecl_permute_bitrev_to_custom/Makefile b/proofs/cbmc/polyvecl_permute_bitrev_to_custom/Makefile
new file mode 100644
index 000000000..370d3571e
--- /dev/null
+++ b/proofs/cbmc/polyvecl_permute_bitrev_to_custom/Makefile
@@ -0,0 +1,55 @@
+# Copyright (c) The mldsa-native project authors
+# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
+
+include ../Makefile_params.common
+
+HARNESS_ENTRY = harness
+HARNESS_FILE = polyvecl_permute_bitrev_to_custom_harness
+
+# This should be a unique identifier for this proof, and will appear on the
+# Litani dashboard. It can be human-readable and contain spaces if you wish.
+PROOF_UID = polyvecl_permute_bitrev_to_custom
+
+DEFINES +=
+INCLUDES +=
+
+REMOVE_FUNCTION_BODY +=
+UNWINDSET +=
+
+PROOF_SOURCES += $(PROOFDIR)/$(HARNESS_FILE).c
+PROJECT_SOURCES += $(SRCDIR)/mldsa/src/polyvec.c
+
+CHECK_FUNCTION_CONTRACTS=mld_polyvecl_permute_bitrev_to_custom
+USE_FUNCTION_CONTRACTS=
+APPLY_LOOP_CONTRACTS=on
+USE_DYNAMIC_FRAMES=1
+
+# Disable any setting of EXTERNAL_SAT_SOLVER, and choose SMT backend instead
+EXTERNAL_SAT_SOLVER=
+CBMCFLAGS=--smt2 --slice-formula --no-array-field-sensitivity
+
+FUNCTION_NAME = polyvecl_permute_bitrev_to_custom
+
+# If this proof is found to consume huge amounts of RAM, you can set the
+# EXPENSIVE variable. With new enough versions of the proof tools, this will
+# restrict the number of EXPENSIVE CBMC jobs running at once. See the
+# documentation in Makefile.common under the "Job Pools" heading for details.
+# EXPENSIVE = true
+
+# This function is large enough to need...
+CBMC_OBJECT_BITS = 12
+
+# If you require access to a file-local ("static") function or object to conduct
+# your proof, set the following (and do not include the original source file
+# ("mldsa/poly.c") in PROJECT_SOURCES).
+# REWRITTEN_SOURCES = $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i
+# include ../Makefile.common
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_SOURCE = $(SRCDIR)/mldsa/poly.c
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_FUNCTIONS = foo bar
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_OBJECTS = baz
+# Care is required with variables on the left-hand side: REWRITTEN_SOURCES must
+# be set before including Makefile.common, but any use of variables on the
+# left-hand side requires those variables to be defined. Hence, _SOURCE,
+# _FUNCTIONS, _OBJECTS is set after including Makefile.common.
+
+include ../Makefile.common
diff --git a/proofs/cbmc/polyvecl_permute_bitrev_to_custom/polyvecl_permute_bitrev_to_custom_harness.c b/proofs/cbmc/polyvecl_permute_bitrev_to_custom/polyvecl_permute_bitrev_to_custom_harness.c
new file mode 100644
index 000000000..83d58ff7c
--- /dev/null
+++ b/proofs/cbmc/polyvecl_permute_bitrev_to_custom/polyvecl_permute_bitrev_to_custom_harness.c
@@ -0,0 +1,12 @@
+// Copyright (c) The mldsa-native project authors
+// SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
+
+#include "polyvec.h"
+
+void mld_polyvecl_permute_bitrev_to_custom(mld_polyvecl *v);
+
+void harness(void)
+{
+  mld_polyvecl *v;
+  mld_polyvecl_permute_bitrev_to_custom(v);
+}
diff --git a/proofs/cbmc/polyvecl_permute_bitrev_to_custom_native/Makefile b/proofs/cbmc/polyvecl_permute_bitrev_to_custom_native/Makefile
new file mode 100644
index 000000000..893a26dec
--- /dev/null
+++ b/proofs/cbmc/polyvecl_permute_bitrev_to_custom_native/Makefile
@@ -0,0 +1,54 @@
+# Copyright (c) The mlkem-native project authors
+# Copyright (c) The mldsa-native project authors
+# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
+
+include ../Makefile_params.common
+
+HARNESS_ENTRY = harness
+HARNESS_FILE = polyvecl_permute_bitrev_to_custom_native_harness
+
+# This should be a unique identifier for this proof, and will appear on the
+# Litani dashboard. It can be human-readable and contain spaces if you wish.
+PROOF_UID = mld_polyvecl_permute_bitrev_to_custom_native
+
+DEFINES += -DMLD_CONFIG_USE_NATIVE_BACKEND_ARITH -DMLD_CONFIG_ARITH_BACKEND_FILE="\"dummy_backend.h\""
+INCLUDES +=
+UNWINDSET +=
+
+REMOVE_FUNCTION_BODY +=
+
+PROOF_SOURCES += $(PROOFDIR)/$(HARNESS_FILE).c
+PROJECT_SOURCES += $(SRCDIR)/mldsa/src/polyvec.c
+
+CHECK_FUNCTION_CONTRACTS=mld_polyvecl_permute_bitrev_to_custom
+USE_FUNCTION_CONTRACTS= mld_poly_permute_bitrev_to_custom
+APPLY_LOOP_CONTRACTS=on
+USE_DYNAMIC_FRAMES=1
+
+# Disable any setting of EXTERNAL_SAT_SOLVER, and choose SMT backend instead
+EXTERNAL_SAT_SOLVER=
+CBMCFLAGS=--smt2 --slice-formula --no-array-field-sensitivity
+
+FUNCTION_NAME = mld_polyvecl_permute_bitrev_to_custom_native
+
+# If this proof is found to consume huge amounts of RAM, you can set the
+# EXPENSIVE variable. With new enough versions of the proof tools, this will
+# restrict the number of EXPENSIVE CBMC jobs running at once. See the
+# documentation in Makefile.common under the "Job Pools" heading for details.
+# EXPENSIVE = true
+CBMC_OBJECT_BITS = 10
+
+# If you require access to a file-local ("static") function or object to conduct
+# your proof, set the following (and do not include the original source file
+# ("mldsa/poly.c") in PROJECT_SOURCES).
+# REWRITTEN_SOURCES = $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i
+# include ../Makefile.common
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_SOURCE = $(SRCDIR)/mldsa/poly.c
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_FUNCTIONS = foo bar
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_OBJECTS = baz
+# Care is required with variables on the left-hand side: REWRITTEN_SOURCES must
+# be set before including Makefile.common, but any use of variables on the
+# left-hand side requires those variables to be defined. Hence, _SOURCE,
+# _FUNCTIONS, _OBJECTS is set after including Makefile.common.
+
+include ../Makefile.common
diff --git a/proofs/cbmc/polyvecl_permute_bitrev_to_custom_native/polyvecl_permute_bitrev_to_custom_native_harness.c b/proofs/cbmc/polyvecl_permute_bitrev_to_custom_native/polyvecl_permute_bitrev_to_custom_native_harness.c
new file mode 100644
index 000000000..83d58ff7c
--- /dev/null
+++ b/proofs/cbmc/polyvecl_permute_bitrev_to_custom_native/polyvecl_permute_bitrev_to_custom_native_harness.c
@@ -0,0 +1,12 @@
+// Copyright (c) The mldsa-native project authors
+// SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
+
+#include "polyvec.h"
+
+void mld_polyvecl_permute_bitrev_to_custom(mld_polyvecl *v);
+
+void harness(void)
+{
+  mld_polyvecl *v;
+  mld_polyvecl_permute_bitrev_to_custom(v);
+}
diff --git a/scripts/check-contracts b/scripts/check-contracts
index 610458b13..2ad5a114e 100755
--- a/scripts/check-contracts
+++ b/scripts/check-contracts
@@ -43,6 +43,9 @@ def gen_contracts():
 def is_exception(funcname):
     # The functions passing this filter are known not to have a proof
 
+    if funcname == 'poly_permute_bitrev_to_custom':
+        return True
+    
     if funcname.endswith("_native") or funcname.endswith("_asm"):
         # CBMC proofs are axiomatized against contracts of the backends
         return True