diff --git a/pkgs/by-name/li/libmcrypt/package.nix b/pkgs/by-name/li/libmcrypt/package.nix
index 8d5118c8643f..31b8f5a9c4e9 100644
--- a/pkgs/by-name/li/libmcrypt/package.nix
+++ b/pkgs/by-name/li/libmcrypt/package.nix
@@ -6,13 +6,13 @@
   disablePosixThreads ? false,
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   pname = "libmcrypt";
   version = "2.5.8";
 
   src = fetchurl {
-    url = "mirror://sourceforge/mcrypt/Libmcrypt/${version}/libmcrypt-${version}.tar.gz";
-    sha256 = "0gipgb939vy9m66d3k8il98rvvwczyaw2ixr8yn6icds9c3nrsz4";
+    url = "mirror://sourceforge/mcrypt/Libmcrypt/${finalAttrs.version}/libmcrypt-${finalAttrs.version}.tar.gz";
+    hash = "sha256-5OtsB0u6sWisR7lHwZX/jO+dUaIRzdGMqcnvNNJ6Nz4=";
   };
 
   buildInputs = lib.optional stdenv.hostPlatform.isDarwin cctools;
@@ -34,7 +34,7 @@ stdenv.mkDerivation rec {
     description = "Replacement for the old crypt() package and crypt(1) command, with extensions";
     mainProgram = "libmcrypt-config";
     homepage = "https://mcrypt.sourceforge.net";
-    license = "GPL";
+    license = lib.licenses.lgpl21Plus;
     platforms = lib.platforms.all;
   };
-}
+})
diff --git a/pkgs/by-name/mc/mcrypt/package.nix b/pkgs/by-name/mc/mcrypt/package.nix
index 711268aef320..cd410b7c77bf 100644
--- a/pkgs/by-name/mc/mcrypt/package.nix
+++ b/pkgs/by-name/mc/mcrypt/package.nix
@@ -6,13 +6,13 @@
   libmhash,
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   version = "2.6.8";
   pname = "mcrypt";
 
   src = fetchurl {
-    url = "mirror://sourceforge/mcrypt/MCrypt/${version}/mcrypt-${version}.tar.gz";
-    sha256 = "5145aa844e54cca89ddab6fb7dd9e5952811d8d787c4f4bf27eb261e6c182098";
+    url = "mirror://sourceforge/mcrypt/MCrypt/${finalAttrs.version}/mcrypt-${finalAttrs.version}.tar.gz";
+    hash = "sha256-UUWqhE5UzKid2rb7fdnllSgR2NeHxPS/J+smHmwYIJg=";
   };
 
   patches = [
@@ -28,9 +28,7 @@ stdenv.mkDerivation rec {
     libmhash
   ];
 
-  env = lib.optionalAttrs stdenv.cc.isClang {
-    NIX_CFLAGS_COMPILE = "-Wno-implicit-function-declaration";
-  };
+  env.NIX_CFLAGS_COMPILE = "-Wno-error=implicit-function-declaration";
 
   meta = {
     description = "Replacement for old UNIX crypt(1)";
@@ -40,8 +38,8 @@ stdenv.mkDerivation rec {
       ever-wider range of algorithms and modes.
     '';
     homepage = "https://mcrypt.sourceforge.net";
-    license = lib.licenses.gpl3Only;
+    license = lib.licenses.gpl3Plus;
     platforms = lib.platforms.all;
     maintainers = [ lib.maintainers.qknight ];
   };
-}
+})