diff --git a/.github/workflows/Simple.yml b/.github/workflows/Simple.yml
index 610e813..02f63af 100644
--- a/.github/workflows/Simple.yml
+++ b/.github/workflows/Simple.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.31.0, 1.41.0, 1.51.0, stable, beta, nightly]
+        rust: [1.36.0, 1.41.0, 1.46.0, 1.51.0, stable, beta, nightly]
     steps:
       - uses: actions/checkout@v2
         with:
diff --git a/README.md b/README.md
index e60ec24..b344bf5 100644
--- a/README.md
+++ b/README.md
@@ -90,7 +90,7 @@ minimal-lexical should also work on a wide variety of other architectures and IS
 
 # Minimum Version Support
 
-Minimal-lexical is tested to support Rustc 1.31+, including stable, beta, and nightly. Please report any errors compiling a supported lexical version on a compatible Rustc version.
+Minimal-lexical is tested to support Rustc 1.36+, including stable, beta, and nightly. Please report any errors compiling a supported lexical version on a compatible Rustc version. Please note we may increment the MSRV for compiler versions older than 18 months, to support at least the current Debian stable version, without breaking changes.
 
 # Changelog
 
diff --git a/src/bellerophon.rs b/src/bellerophon.rs
index 8966710..b5433f1 100644
--- a/src/bellerophon.rs
+++ b/src/bellerophon.rs
@@ -317,7 +317,8 @@ pub fn mul(x: &ExtendedFloat, y: &ExtendedFloat) -> ExtendedFloat {
     debug_assert!(y.mant >> 32 != 0);
 
     // Extract high-and-low masks.
-    const LOMASK: u64 = u32::MAX as u64;
+    // Mask is u32::MAX for older Rustc versions.
+    const LOMASK: u64 = 0xffff_ffff as u64;
     let x1 = x.mant >> 32;
     let x0 = x.mant & LOMASK;
     let y1 = y.mant >> 32;
@@ -363,7 +364,7 @@ pub struct BellerophonPowers {
 /// Allow indexing of values without bounds checking
 impl BellerophonPowers {
     #[inline]
-    pub const fn get_small(&self, index: usize) -> ExtendedFloat {
+    pub fn get_small(&self, index: usize) -> ExtendedFloat {
         let mant = self.small[index];
         let exp = (1 - 64) + ((self.log2 * index as i64) >> self.log2_shift);
         ExtendedFloat {
@@ -373,7 +374,7 @@ impl BellerophonPowers {
     }
 
     #[inline]
-    pub const fn get_large(&self, index: usize) -> ExtendedFloat {
+    pub fn get_large(&self, index: usize) -> ExtendedFloat {
         let mant = self.large[index];
         let biased_e = index as i64 * self.step as i64 - self.bias as i64;
         let exp = (1 - 64) + ((self.log2 * biased_e) >> self.log2_shift);
@@ -384,7 +385,7 @@ impl BellerophonPowers {
     }
 
     #[inline]
-    pub const fn get_small_int(&self, index: usize) -> u64 {
+    pub fn get_small_int(&self, index: usize) -> u64 {
         self.small_int[index]
     }
 }
diff --git a/src/mask.rs b/src/mask.rs
index 577ad08..1957c8b 100644
--- a/src/mask.rs
+++ b/src/mask.rs
@@ -17,7 +17,8 @@ pub fn lower_n_mask(n: u64) -> u64 {
     debug_assert!(n <= 64, "lower_n_mask() overflow in shl.");
 
     match n == 64 {
-        true => u64::MAX,
+        // u64::MAX for older Rustc versions.
+        true => 0xffff_ffff_ffff_ffff,
         false => (1 << n) - 1,
     }
 }
diff --git a/src/num.rs b/src/num.rs
index 1608a13..7e10ee2 100644
--- a/src/num.rs
+++ b/src/num.rs
@@ -84,7 +84,8 @@ pub trait Float:
     const CARRY_MASK: u64;
 
     /// Bias for marking an invalid extended float.
-    const INVALID_FP: i32 = i16::MIN as i32;
+    // Value is `i16::MIN`, using hard-coded constants for older Rustc versions.
+    const INVALID_FP: i32 = -0x8000;
 
     // Maximum mantissa for the fast-path (`1 << 53` for f64).
     const MAX_MANTISSA_FAST_PATH: u64 = 2_u64 << Self::MANTISSA_SIZE;
@@ -163,7 +164,7 @@ pub trait Float:
         };
 
         #[cfg(feature = "compact")]
-        return (radix as u64).wrapping_pow(exponent as u32);
+        return (radix as u64).pow(exponent as u32);
     }
 
     /// Returns true if the float is a denormal.
@@ -270,7 +271,8 @@ impl Float for f32 {
 
     #[inline]
     fn from_bits(u: u64) -> f32 {
-        debug_assert!(u <= u32::MAX as u64);
+        // Constant is `u32::MAX` for older Rustc versions.
+        debug_assert!(u <= 0xffff_ffff);
         f32::from_bits(u as u32)
     }
 
diff --git a/src/stackvec.rs b/src/stackvec.rs
index 06071eb..23a1146 100644
--- a/src/stackvec.rs
+++ b/src/stackvec.rs
@@ -45,7 +45,8 @@ impl StackVec {
     /// Safe as long as `len` is less than `BIGINT_LIMBS`.
     #[inline]
     pub unsafe fn set_len(&mut self, len: usize) {
-        debug_assert!(len <= u16::MAX as usize);
+        // Constant is `u16::MAX` for older Rustc versions.
+        debug_assert!(len <= 0xffff);
         debug_assert!(len <= bigint::BIGINT_LIMBS);
         self.length = len as u16;
     }