diff --git a/core/zlib/build b/core/zlib/build
index 39962de2..e77abad9 100755
--- a/core/zlib/build
+++ b/core/zlib/build
@@ -2,6 +2,8 @@
 
 export CFLAGS="$CFLAGS -fPIC"
 
+patch -p1 < Fix-CC-logic-in-configure.patch
+
 ./configure \
     --prefix=/usr
 
diff --git a/core/zlib/checksums b/core/zlib/checksums
index ec1ba07f..587b875b 100644
--- a/core/zlib/checksums
+++ b/core/zlib/checksums
@@ -1 +1,2 @@
-c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1
+91844808532e5ce316b3c010929493c0244f3d37593afd6de04f71821d5136d9
+f35eb05334a4f8d7b40b6c5610a6369f654863b5fa1a19c2507888f918025238
diff --git a/core/zlib/patches/Fix-CC-logic-in-configure.patch b/core/zlib/patches/Fix-CC-logic-in-configure.patch
new file mode 100644
index 00000000..f34c4044
--- /dev/null
+++ b/core/zlib/patches/Fix-CC-logic-in-configure.patch
@@ -0,0 +1,43 @@
+From 80d086357a55b94a13e43756cf3e131f25eef0e4 Mon Sep 17 00:00:00 2001
+From: Sam James <sam@gentoo.org>
+Date: Mon, 28 Mar 2022 08:40:45 +0100
+Subject: [PATCH] Fix CC logic in configure
+
+In https://github.com/madler/zlib/commit/e9a52aa129efe3834383e415580716a7c4027f8d,
+the logic was changed to try check harder for GCC, but it dropped
+the default setting of cc=${CC}. It was throwing away any pre-set CC value as
+a result.
+
+The rest of the script then cascades down a bad path because it's convinced
+it's not GCC or a GCC-like compiler.
+
+This led to e.g. misdetection of inability to build shared libs
+for say, multilib cases (w/ CC being one thing from the environment being used
+for one test (e.g. x86_64-unknown-linux-gnu-gcc -m32 and then 'cc' used for
+shared libs (but missing "-m32"!)). Obviously just one example of how
+the old logic could break.
+
+This restores the old default of 'CC' if nothing overrides it later
+in configure.
+
+Bug: https://bugs.gentoo.org/836308
+Signed-off-by: Sam James <sam@gentoo.org>
+---
+ configure | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/configure b/configure
+index 52ff4a04e..3fa3e8618 100755
+--- a/configure
++++ b/configure
+@@ -174,7 +174,10 @@ if test -z "$CC"; then
+   else
+     cc=${CROSS_PREFIX}cc
+   fi
++else
++  cc=${CC}
+ fi
++
+ cflags=${CFLAGS-"-O3"}
+ # to force the asm version use: CFLAGS="-O3 -DASMV" ./configure
+ case "$cc" in
diff --git a/core/zlib/sources b/core/zlib/sources
index c52cb60b..27b7fe11 100644
--- a/core/zlib/sources
+++ b/core/zlib/sources
@@ -1 +1,2 @@
 https://zlib.net/zlib-VERSION.tar.gz
+patches/Fix-CC-logic-in-configure.patch
diff --git a/core/zlib/version b/core/zlib/version
index 41acf3fe..d9f2a341 100644
--- a/core/zlib/version
+++ b/core/zlib/version
@@ -1 +1 @@
-1.2.11 3
+1.2.12 1