diff --git a/Cargo.lock b/Cargo.lock
index 54bcd9b..d73ba74 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1619,9 +1619,9 @@ checksum = "1ee0548b407f2cbfb0228b65cd91e09be63cfd4e883b5a997b3a4e2158febe8f"
 
 [[package]]
 name = "verus_builtin_macros"
-version = "0.0.0-2026-03-01-0109"
+version = "0.0.0-2026-03-08-0103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b7bc3f4a9f628702b5af08de7a3fb4605001a4abf2e8af6c12d04075410846d"
+checksum = "5521119b3fd13d0b1748a0fef287a9aeeb247dd702cd7b15f96e5b9eb95f002b"
 dependencies = [
  "proc-macro2 1.0.106",
  "quote 1.0.44",
@@ -1672,9 +1672,9 @@ checksum = "5c3082ca00d5a5ef149bb8b555a72ae84c9c59f7250f013ac822ac2e49b19c64"
 
 [[package]]
 name = "vstd"
-version = "0.0.0-2026-03-01-0109"
+version = "0.0.0-2026-03-08-0103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "acfd39a5498898d5f9acc93313abfa9938ff4d23006468518cd83e8f6bb063d7"
+checksum = "e19bb62988a03cc130a39566b58ece7677ecb26e70a05ca95bf06f7169ca6af5"
 dependencies = [
  "verus_builtin",
  "verus_builtin_macros",
diff --git a/Cargo.toml b/Cargo.toml
index 8ae75d7..eafb14a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -136,7 +136,7 @@ indexmap = { version = "2.12.1", default-features = false, features = ["serde"],
 bincode = { version = "2.0.1", default-features = false, features = ["alloc", "serde"], optional = true }
 
 # Use Verus for verification
-vstd = { version = "0.0.0-2026-03-01-0109" }
+vstd = { version = "0.0.0-2026-03-08-0103" }
 
 [dev-dependencies]
 anyhow = "1.0.45"
diff --git a/src/number.rs b/src/number.rs
index fc910d3..9047219 100644
--- a/src/number.rs
+++ b/src/number.rs
@@ -539,8 +539,31 @@ impl FromStr for Number {
     }
 }
 
+verus! {
+
+#[cfg(verus_keep_ghost)]
+impl PartialEqSpecImpl for Number {
+    open spec fn obeys_eq_spec() -> bool
+    {
+        false
+    }
+
+    open spec fn eq_spec(&self, other: &Self) -> bool
+    {
+        *self == *other
+    }
+}
+
 impl PartialEq for Number {
-    fn eq(&self, other: &Self) -> bool {
+    fn eq(&self, other: &Self) -> (result: bool)
+        ensures
+            match (self@, other@) {
+                (NumberView::Integer(n1), NumberView::Integer(n2)) => result == (n1 == n2),
+                _ => true,
+            },
+    {
+        proof { axiom_bigint_obeys_eq_spec(); }
+
         if let (Some(a), Some(b)) = (self.to_bigint_owned(), other.to_bigint_owned()) {
             return a == b;
         }
@@ -554,6 +577,8 @@ impl PartialEq for Number {
     }
 }
 
+}
+
 impl Eq for Number {}
 
 impl Ord for Number {
diff --git a/src/verusspec/bigint.rs b/src/verusspec/bigint.rs
index 8e419ae..08bc4aa 100644
--- a/src/verusspec/bigint.rs
+++ b/src/verusspec/bigint.rs
@@ -50,6 +50,23 @@ pub assume_specification[ <BigInt as num_traits::Signed>::is_negative ](x: &BigI
         res == (x@ < 0),
 ;
 
+// PartialEq
+
+pub axiom fn axiom_bigint_obeys_eq_spec()
+    ensures
+        <BigInt as vstd::std_specs::cmp::PartialEqSpec>::obeys_eq_spec(),
+;
+
+pub axiom fn axiom_bigint_obeys_partial_cmp_spec()
+    ensures
+        <BigInt as vstd::std_specs::cmp::PartialOrdSpec>::obeys_partial_cmp_spec(),
+;
+
+pub assume_specification[ <BigInt as core::cmp::PartialEq>::eq ](x: &BigInt, y: &BigInt) -> (res: bool)
+    ensures
+        res == (x@ == y@),
+;
+
 // From
 
 pub assume_specification[ <BigInt as core::convert::From<i64>>::from ](i: i64) -> (res: BigInt)
diff --git a/src/verusspec/float.rs b/src/verusspec/float.rs
index 79919a4..db3a171 100644
--- a/src/verusspec/float.rs
+++ b/src/verusspec/float.rs
@@ -95,6 +95,13 @@ pub assume_specification [ f64::abs ](f: f64) -> (res: f64)
         res == spec_f64_abs(f),
 ;
 
+pub uninterp spec fn spec_f64_is_nan(f: f64) -> bool;
+
+pub assume_specification [ f64::is_nan ](f: f64) -> (res: bool)
+    ensures
+        res == spec_f64_is_nan(f),
+;
+
 pub uninterp spec fn spec_f64_neg_infinity() -> f64;
 
 #[inline]