diff --git a/ports/eigen3/fix-vectorized-reductions-half.patch b/ports/eigen3/fix-vectorized-reductions-half.patch
new file mode 100644
index 0000000000..1c5e592db5
--- /dev/null
+++ b/ports/eigen3/fix-vectorized-reductions-half.patch
@@ -0,0 +1,26 @@
+diff --git a/Eigen/src/Core/PartialReduxEvaluator.h b/Eigen/src/Core/PartialReduxEvaluator.h
+index 29abf35..4051fcf 100644
+--- a/Eigen/src/Core/PartialReduxEvaluator.h
++++ b/Eigen/src/Core/PartialReduxEvaluator.h
+@@ -54,12 +54,19 @@ struct packetwise_redux_traits
+ /* Value to be returned when size==0 , by default let's return 0 */
+ template<typename PacketType,typename Func>
+ EIGEN_DEVICE_FUNC
+-PacketType packetwise_redux_empty_value(const Func& ) { return pset1<PacketType>(0); }
++PacketType packetwise_redux_empty_value(const Func& ) {
++  const typename unpacket_traits<PacketType>::type zero(0);
++  return pset1<PacketType>(zero);
++}
++
+ 
+ /* For products the default is 1 */
+ template<typename PacketType,typename Scalar>
+ EIGEN_DEVICE_FUNC
+-PacketType packetwise_redux_empty_value(const scalar_product_op<Scalar,Scalar>& ) { return pset1<PacketType>(1); }
++PacketType packetwise_redux_empty_value(const scalar_product_op<Scalar,Scalar>& ) {
++  return pset1<PacketType>(Scalar(1));
++}
++
+ 
+ /* Perform the actual reduction */
+ template<typename Func, typename Evaluator,
diff --git a/ports/eigen3/portfile.cmake b/ports/eigen3/portfile.cmake
index 34dd3da7a2..d6725d44a0 100644
--- a/ports/eigen3/portfile.cmake
+++ b/ports/eigen3/portfile.cmake
@@ -7,7 +7,9 @@ vcpkg_from_gitlab(
     REF 3.4.0
     SHA512 ba75ecb760e32acf4ceaf27115468e65d4f77c44f8d519b5a13e7940af2c03a304ad433368cb6d55431f307c5c39e2666ab41d34442db3cf441638e51f5c3b6a
     HEAD_REF master
-    PATCHES remove_configure_checks.patch # This removes unnecessary configure checks. Eigen3 just installs headers not anything more.
+    PATCHES
+        remove_configure_checks.patch # This removes unnecessary configure checks. Eigen3 just installs headers not anything more.
+        fix-vectorized-reductions-half.patch # Remove this patch in the next update
 )
 
 vcpkg_cmake_configure(
diff --git a/ports/eigen3/vcpkg.json b/ports/eigen3/vcpkg.json
index 022fe4facd..30bf5aa3e1 100644
--- a/ports/eigen3/vcpkg.json
+++ b/ports/eigen3/vcpkg.json
@@ -1,7 +1,7 @@
 {
   "name": "eigen3",
   "version": "3.4.0",
-  "port-version": 1,
+  "port-version": 2,
   "description": "C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.",
   "homepage": "http://eigen.tuxfamily.org",
   "license": "MPL-2.0",
diff --git a/versions/baseline.json b/versions/baseline.json
index b793999df7..80be147c2f 100644
--- a/versions/baseline.json
+++ b/versions/baseline.json
@@ -2026,7 +2026,7 @@
     },
     "eigen3": {
       "baseline": "3.4.0",
-      "port-version": 1
+      "port-version": 2
     },
     "elfio": {
       "baseline": "3.10",
diff --git a/versions/e-/eigen3.json b/versions/e-/eigen3.json
index 9b886bc0c6..850e31dcc8 100644
--- a/versions/e-/eigen3.json
+++ b/versions/e-/eigen3.json
@@ -1,5 +1,10 @@
 {
   "versions": [
+    {
+      "git-tree": "250d10d414a5542aaf832350264498ba727c4c03",
+      "version": "3.4.0",
+      "port-version": 2
+    },
     {
       "git-tree": "4b40326590314e1f3a08c75e83a42d0738040b68",
       "version": "3.4.0",