diff --git a/docs/release.rst b/docs/release.rst
index 0bf6f337..5d64406f 100644
--- a/docs/release.rst
+++ b/docs/release.rst
@@ -16,6 +16,10 @@ Fixes
 * Cleanup ``crc32c`` soft dependency.
   By :user:`John Kirkham <jakirkham>`, :issue:`637`
 
+Improvements
+~~~~~~~~~~~~
+* Add `noexcept` to `_utils` C-equiv functions
+  By :user:`John Kirkham <jakirkham>`, :issue:`641`.
 
 .. _release_0.14.0:
 
diff --git a/numcodecs/_utils.pxd b/numcodecs/_utils.pxd
index c2614e12..c76f3e18 100644
--- a/numcodecs/_utils.pxd
+++ b/numcodecs/_utils.pxd
@@ -8,14 +8,14 @@
 from libc.stdint cimport uint8_t, uint32_t
 
 
-cdef inline void store_le32(uint8_t c[4], uint32_t i) nogil:
+cdef inline void store_le32(uint8_t c[4], uint32_t i) noexcept nogil:
     c[0] = i & 0xFF
     c[1] = (i >> 8) & 0xFF
     c[2] = (i >> 16) & 0xFF
     c[3] = (i >> 24) & 0xFF
 
 
-cdef inline uint32_t load_le32(const uint8_t c[4]) nogil:
+cdef inline uint32_t load_le32(const uint8_t c[4]) noexcept nogil:
     return (
         c[0] |
         (c[1] << 8) |