diff --git a/CMakeLists.txt b/CMakeLists.txt
index b6cb0b2b..fd608697 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required (VERSION 3.15)
 
-set(libcmaes_VERSION 0.10.2)
+set(libcmaes_VERSION 0.10.3)
 
 project (libcmaes
   VERSION ${libcmaes_VERSION}
@@ -28,6 +28,7 @@ option (LIBCMAES_BUILD_TESTS "build tests" OFF)
 option (LIBCMAES_BUILD_EXAMPLES "build examples" ${LIBCMAES_TOP_LEVEL})
 option (LIBCMAES_USE_OPENMP "Use OpenMP for multithreading" ON)
 option (LIBCMAES_ENABLE_SURROG "support for surrogates" ON)
+option (LIBCMAES_EIGEN_5 "Use Eigen v5" OFF)
 
 # Offer the user the choice of overriding the installation directories
 set (INSTALL_LIB_DIR lib${LIB_SUFFIX}
@@ -78,8 +79,44 @@ if(LIBCMAES_BUILD_PYTHON)
   endif ()
 endif()
 
+if (LIBCMAES_EIGEN_5)
+  set (LIBCMAES_EIGEN_MIN_VERSION 5.0.0)
+else ()
+  set (LIBCMAES_EIGEN_MIN_VERSION 3.4.0)
+endif ()
+
+find_package (Eigen3 REQUIRED)
+
+set (LIBCMAES_EIGEN_FOUND_VERSION ${Eigen3_VERSION})
+if (NOT LIBCMAES_EIGEN_FOUND_VERSION AND DEFINED EIGEN3_VERSION_STRING)
+  set (LIBCMAES_EIGEN_FOUND_VERSION ${EIGEN3_VERSION_STRING})
+endif ()
+
+if (NOT LIBCMAES_EIGEN_FOUND_VERSION)
+  message (FATAL_ERROR "Could not determine the Eigen version exposed by package Eigen3.")
+endif ()
 
-find_package (Eigen3 3.4.0 REQUIRED)
+set (LIBCMAES_EIGEN_LOCATION "")
+if (DEFINED Eigen3_DIR AND NOT "${Eigen3_DIR}" STREQUAL "")
+  set (LIBCMAES_EIGEN_LOCATION "package dir: ${Eigen3_DIR}")
+elseif (DEFINED EIGEN3_ROOT_DIR AND NOT "${EIGEN3_ROOT_DIR}" STREQUAL "")
+  set (LIBCMAES_EIGEN_LOCATION "root: ${EIGEN3_ROOT_DIR}")
+elseif (DEFINED EIGEN3_INCLUDE_DIRS AND NOT "${EIGEN3_INCLUDE_DIRS}" STREQUAL "")
+  set (LIBCMAES_EIGEN_LOCATION "includes: ${EIGEN3_INCLUDE_DIRS}")
+endif ()
+
+if (LIBCMAES_EIGEN_LOCATION)
+  message (STATUS "Using Eigen ${LIBCMAES_EIGEN_FOUND_VERSION} (${LIBCMAES_EIGEN_LOCATION})")
+else ()
+  message (STATUS "Using Eigen ${LIBCMAES_EIGEN_FOUND_VERSION}")
+endif ()
+
+if (LIBCMAES_EIGEN_FOUND_VERSION VERSION_LESS LIBCMAES_EIGEN_MIN_VERSION)
+  message (
+    FATAL_ERROR
+      "LIBCMAES_EIGEN_5=${LIBCMAES_EIGEN_5} requires Eigen >= ${LIBCMAES_EIGEN_MIN_VERSION}, "
+      "but found ${LIBCMAES_EIGEN_FOUND_VERSION}. Set Eigen3_DIR or CMAKE_PREFIX_PATH to an appropriate Eigen installation.")
+endif ()
 
 if (LIBCMAES_USE_OPENMP)
   find_package (OpenMP QUIET)
diff --git a/appveyor.yml b/appveyor.yml
index 0fdd1cf8..f43c59be 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -2,14 +2,34 @@ clone_folder: C:\projects\libcmaes
 environment:
   matrix:
     - CMAKE_PLATFORM: "Visual Studio 14 2015"
+      EIGEN_VERSION: "3.3.4"
+      EIGEN_URL: "https://bitbucket.org/eigen/eigen/get/3.3.4.tar.gz"
+      EIGEN_ZIP: "3.3.4.tar.gz"
+      LIBCMAES_EIGEN_5: OFF
+    - CMAKE_PLATFORM: "Visual Studio 14 2015"
+      EIGEN_VERSION: "5.0.0"
+      EIGEN_URL: "https://gitlab.com/libeigen/eigen/-/archive/5.0.0/eigen-5.0.0.tar.gz"
+      EIGEN_ZIP: "eigen-5.0.0.tar.gz"
+      LIBCMAES_EIGEN_5: ON
+    - CMAKE_PLATFORM: "Visual Studio 14 2015 Win64"
+      EIGEN_VERSION: "3.3.4"
+      EIGEN_URL: "https://bitbucket.org/eigen/eigen/get/3.3.4.tar.gz"
+      EIGEN_ZIP: "3.3.4.tar.gz"
+      LIBCMAES_EIGEN_5: OFF
     - CMAKE_PLATFORM: "Visual Studio 14 2015 Win64"
+      EIGEN_VERSION: "5.0.0"
+      EIGEN_URL: "https://gitlab.com/libeigen/eigen/-/archive/5.0.0/eigen-5.0.0.tar.gz"
+      EIGEN_ZIP: "eigen-5.0.0.tar.gz"
+      LIBCMAES_EIGEN_5: ON
 
 install:
   - cinstall: python
-  - appveyor-retry appveyor DownloadFile https://bitbucket.org/eigen/eigen/get/3.3.4.tar.gz
-  - 7z x 3.3.4.tar.gz -oc:\projects > nul
-  - 7z x c:\projects\3.3.4.tar -oc:\projects > nul
-  - cd c:\projects\eigen-eigen-5a0156e40feb
+  - appveyor-retry appveyor DownloadFile "%EIGEN_URL%" -FileName eigen.tar.gz
+  - 7z x eigen.tar.gz -oc:\projects > nul
+  - 7z x c:\projects\eigen.tar -oc:\projects > nul
+  - cd c:\projects
+  - for /d %%i in (eigen-*) do set EIGEN_DIR=%%i
+  - cd %EIGEN_DIR%
   - mkdir build && cd build
   - cmake -G "%CMAKE_PLATFORM%" -DCMAKE_INSTALL_PREFIX=c:\Libraries\eigen -DCMAKE_BUILD_TYPE=Release ..
   - cmake --build . --config Release --target install
@@ -17,6 +37,6 @@ install:
 build_script:
   - cd c:\projects\libcmaes
   - mkdir build && cd build
-  - cmake -G "%CMAKE_PLATFORM%" -DCMAKE_INSTALL_PREFIX=c:\Libraries\libcmaes -DEigen3_DIR=c:\Libraries\eigen\share\eigen3\cmake -DBOOST_ROOT="C:/Libraries/boost_1_63_0" ..
+  - cmake -G "%CMAKE_PLATFORM%" -DCMAKE_INSTALL_PREFIX=c:\Libraries\libcmaes -DLIBCMAES_EIGEN_5=%LIBCMAES_EIGEN_5% -DEigen3_DIR=c:\Libraries\eigen\share\eigen3\cmake -DBOOST_ROOT="C:/Libraries/boost_1_63_0" ..
   - cmake --build . --config Release --target install
   - ctest -C Release
diff --git a/conanfile.py b/conanfile.py
index 9d12ffac..f6d724b2 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -1,10 +1,9 @@
-import re, os, functools
-
-from conan import ConanFile, tools
 from conan import ConanFile
 from conan.tools.cmake import CMakeToolchain, CMake, cmake_layout
 from conan.tools.files import load
 from conan.tools.env import Environment
+import os
+import re
 
 from conan.tools.scm import Git
 
@@ -12,8 +11,6 @@
 class CmaesConan(ConanFile):
     name = "libcmaes"
 
-    generators = "CMakeDeps"
-
     # Optional metadata
     license = "MIT"
     author = "<Put your name here> <And your email here>"
@@ -23,11 +20,14 @@ class CmaesConan(ConanFile):
 
     # Binary configuration
     settings = "os", "compiler", "build_type", "arch"
+
+    generators = "CMakeDeps"
     options = {
         "shared": [True, False],
         "openmp": [True, False],
         "surrog": [True, False],
         "enable_tests": [True, False],
+        "eigen_5": [True, False],
     }
     default_options = {
         "shared": True,
@@ -35,6 +35,7 @@ class CmaesConan(ConanFile):
         "surrog": True,
         "enable_tests": False,
         "boost/*:without_python": False,
+        "eigen_5": False,
     }
 
     # Sources are located in the same place as this recipe, copy them to the recipe
@@ -55,8 +56,10 @@ def build_requirements(self):
             self.test_requires("boost/1.85.0")
 
     def requirements(self):
-        self.requires("eigen/3.4.0", transitive_headers=True)
-
+        if self.options.eigen_5:
+            self.requires("eigen/5.0.0")
+        else:
+            self.requires("eigen/3.4.0", transitive_headers=True)
         if self.options.openmp and self.settings.os != "Windows":
             self.requires("llvm-openmp/17.0.6", transitive_headers=True)
 
@@ -94,6 +97,7 @@ def generate(self):
         tc.variables["LIBCMAES_ENABLE_SURROG"] = self.options.surrog
         tc.variables["LIBCMAES_BUILD_PYTHON"] = self.options.enable_tests
         tc.variables["LIBCMAES_BUILD_TESTS"] = self.options.enable_tests
+        tc.variables["LIBCMAES_EIGEN_5"] = self.options.eigen_5
         tc.generate()
 
     def build(self):
diff --git a/libcmaes-config.cmake.in b/libcmaes-config.cmake.in
index 8fa61830..89b968da 100644
--- a/libcmaes-config.cmake.in
+++ b/libcmaes-config.cmake.in
@@ -3,7 +3,22 @@
 include(CMakeFindDependencyMacro)
 list (APPEND CMAKE_MODULE_PATH @CMAKE_CURRENT_SOURCE_DIR@/lib/cmake/libcmaes ${CMAKE_CURRENT_LIST_DIR})
 
-find_dependency(Eigen3 @EIGEN3_VERSION@ REQUIRED)
+find_dependency(Eigen3 REQUIRED)
+
+set (_libcmaes_eigen_version "${Eigen3_VERSION}")
+if (NOT _libcmaes_eigen_version AND DEFINED EIGEN3_VERSION_STRING)
+  set (_libcmaes_eigen_version "${EIGEN3_VERSION_STRING}")
+endif ()
+
+if (NOT _libcmaes_eigen_version)
+  message (FATAL_ERROR "Could not determine the Eigen version exposed by package Eigen3.")
+endif ()
+
+if (_libcmaes_eigen_version VERSION_LESS "@LIBCMAES_EIGEN_MIN_VERSION@")
+  message (
+    FATAL_ERROR
+      "libcmaes requires Eigen >= @LIBCMAES_EIGEN_MIN_VERSION@, but found ${_libcmaes_eigen_version}.")
+endif ()
 
 
 if(@LIBCMAES_USE_OPENMP@)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 397bb461..42720890 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -56,7 +56,9 @@ target_include_directories (
   cmaes PUBLIC $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
                $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
   )
+
 target_link_libraries (cmaes PUBLIC Eigen3::Eigen)
+
 if (LIBCMAES_USE_OPENMP)
   target_link_libraries (cmaes PUBLIC OpenMP::OpenMP_CXX)
 endif ()
diff --git a/src/ipopcmastrategy.cc b/src/ipopcmastrategy.cc
index 45fbadcb..1f11b07e 100644
--- a/src/ipopcmastrategy.cc
+++ b/src/ipopcmastrategy.cc
@@ -74,8 +74,8 @@ namespace libcmaes
 	reset_search_state();
 
 	// Update remaining budget
-  int fevals_global = CMAStrategy<TCovarianceUpdate,TGenoPheno>::_nevals;
-  int fevals_remaining = fevals_max - fevals_global;
+	int fevals_global = CMAStrategy<TCovarianceUpdate,TGenoPheno>::_nevals;
+	int fevals_remaining = fevals_max - fevals_global;
 
 	// do not restart if max budget function calls is reached.
 	if (has_max_fevals && fevals_remaining <= 0)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 87dafdab..4a80dcc8 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,7 +1,18 @@
 find_package(gflags REQUIRED)
+
+if (TARGET gflags::gflags)
+  set (LIBCMAES_GFLAGS_TARGET gflags::gflags)
+elseif (TARGET gflags)
+  set (LIBCMAES_GFLAGS_TARGET gflags)
+elseif (DEFINED GFLAGS_TARGET)
+  set (LIBCMAES_GFLAGS_TARGET ${GFLAGS_TARGET})
+else ()
+  message (FATAL_ERROR "Could not determine a usable gflags target.")
+endif ()
+
 macro (cmaes_add_test name)
   add_executable (${name} ${name}.cc)
-  target_link_libraries (${name} cmaes gflags)
+  target_link_libraries (${name} cmaes ${LIBCMAES_GFLAGS_TARGET})
   if(MSVC)
     target_compile_definitions(${name} PUBLIC _USE_MATH_DEFINES)
   endif()