diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+# Version 1.0.18.2
+
+* Add missing dependency on `c2hs`.
+
+* Add missing function: `sodium_free`.
+
+
 # Version 1.0.18.1
 
 * Improve support for opaque C structs (`Storable`, `Ptr`, allocation).
diff --git a/lib/Libsodium.chs b/lib/Libsodium.chs
--- a/lib/Libsodium.chs
+++ b/lib/Libsodium.chs
@@ -306,6 +306,7 @@
   , sodium_bin2base64
   , sodium_bin2hex
   , sodium_compare
+  , sodium_free
   , sodium_hex2bin
   , sodium_increment
   , sodium_init
@@ -795,6 +796,7 @@
 {# fun sodium_hex2bin { id `bin ::: Ptr CUChar', id `bin_maxlen ::: CSize', id `hex ::: Ptr CChar', id `hex_len ::: CSize', id `ignore ::: Ptr CChar', id `bin_len ::: Ptr CSize', id `hex_end ::: Ptr  (Ptr CChar)' } -> `CInt' #}
 
 {# fun sodium_allocarray { id `count ::: CSize', id `size ::: CSize' } -> `Ptr a' castPtr #}
+{# fun sodium_free { castPtr `addr ::: Ptr x' } -> `()' #}
 {# fun sodium_malloc { id `size ::: CSize' } -> `Ptr a' castPtr #}
 {# fun sodium_memcmp { castPtr `b1 ::: Ptr a', castPtr `b2 ::: Ptr a', id `len ::: CSize' } -> `CInt' #}
 {# fun sodium_memzero { castPtr `pnt ::: Ptr x', id `len ::: CSize' } -> `()' #}
diff --git a/libsodium.cabal b/libsodium.cabal
--- a/libsodium.cabal
+++ b/libsodium.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.4
 name: libsodium
-version: 1.0.18.1
+version: 1.0.18.2
 license: ISC
 license-file: LICENSE
 extra-source-files: README.md CHANGELOG.md
@@ -20,6 +20,7 @@
   ghc-options: -Wall -Werror=incomplete-patterns
   build-depends: base == 4.*
   pkgconfig-depends: libsodium == 1.0.18
+  build-tool-depends: c2hs:c2hs
 
 library
   import: basic