diff --git a/Cargo.toml b/Cargo.toml
index a696632b..35236a8b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@
 name = "ndarray"
 version = "0.17.2"
 edition = "2021"
-rust-version = "1.64"
+rust-version = "1.94"
 authors = [
   "Ulrik Sverdrup \"bluss\"",
   "Jim Turner"
diff --git a/src/hpc/compression_curves.rs b/src/hpc/compression_curves.rs
index 517577fb..8dbaf745 100644
--- a/src/hpc/compression_curves.rs
+++ b/src/hpc/compression_curves.rs
@@ -257,7 +257,7 @@ impl ProductQuantizer {
 // Method 5: SPO Bundle (our method)
 // ============================================================================
 
-const PHI: f64 = 1.618_033_988_749_895;
+const PHI: f64 = std::f64::consts::GOLDEN_RATIO;
 
 const fn golden_shift(d: usize) -> usize {
     let raw = (d as f64 / (PHI * PHI)) as usize;
diff --git a/src/hpc/spo_bundle.rs b/src/hpc/spo_bundle.rs
index f434455d..59a46e42 100644
--- a/src/hpc/spo_bundle.rs
+++ b/src/hpc/spo_bundle.rs
@@ -11,8 +11,8 @@
 // Constants
 // ============================================================================
 
-/// Golden ratio φ ≈ 1.618033988749895
-const PHI: f64 = 1.618_033_988_749_895;
+/// Golden ratio φ — Rust 1.94 stdlib constant.
+const PHI: f64 = std::f64::consts::GOLDEN_RATIO;
 
 /// Compute golden shift for dimension d, ensuring odd (gcd=1 with power-of-2 d).
 /// floor(d / φ²), rounded to nearest odd.
diff --git a/src/hpc/surround_metadata.rs b/src/hpc/surround_metadata.rs
index 5d34d43e..b4ddceda 100644
--- a/src/hpc/surround_metadata.rs
+++ b/src/hpc/surround_metadata.rs
@@ -17,8 +17,8 @@ use super::fingerprint::Fingerprint;
 /// Golden angle in radians: 2π / φ² ≈ 2.39996...
 const GOLDEN_ANGLE: f64 = 2.399_963_229_728_653;
 
-/// Euler-Mascheroni constant γ ≈ 0.5772...
-const EULER_GAMMA: f64 = 0.577_215_664_901_532_9;
+/// Euler-Mascheroni constant γ — Rust 1.94 stdlib constant.
+const EULER_GAMMA: f64 = std::f64::consts::EULER_GAMMA;
 
 /// Bundle dimensionality: 8192 f64 values (must be even for Givens pairs)
 const D: usize = 8192;
diff --git a/src/hpc/vml.rs b/src/hpc/vml.rs
index fee79169..63a4bf08 100644
--- a/src/hpc/vml.rs
+++ b/src/hpc/vml.rs
@@ -466,9 +466,7 @@ mod tests {
     fn test_f64_golden_step_hydration_cost() {
         use std::f64::consts;
         // Rust 1.94: std::f64::consts::PHI and GAMMA are stable.
-        // On 1.93: define manually.
-        #[allow(dead_code)]
-        const PHI: f64 = 1.618033988749894848204586834365638118;
+        const PHI: f64 = std::f64::consts::GOLDEN_RATIO;
 
         // Simulate: 4096D f64 vector → Base17-style projection → hydration back
         let d = 4096usize;