diff --git a/.github/workflows/ci-conan.yml b/.github/workflows/ci-conan.yml
index 6acd096a..3fc76a8c 100644
--- a/.github/workflows/ci-conan.yml
+++ b/.github/workflows/ci-conan.yml
@@ -27,7 +27,7 @@ jobs:
       - name: Install prerequisites
         run: |
           apt-get update
-          apt-get install -y pipx cmake doxygen
+          apt-get install -y pipx doxygen
           pipx install conan
           echo "$HOME/.local/bin" >> "$GITHUB_PATH"
       - name: Configure Conan
diff --git a/conanfile.py b/conanfile.py
index 19af82eb..78645781 100755
--- a/conanfile.py
+++ b/conanfile.py
@@ -40,17 +40,17 @@ def set_version(self):
 
     # Dependencies/requirements
     def requirements(self):
-        self.tool_requires("cmake/[>=3.19]")
+        self.tool_requires("cmake/[>=4.0]")
         self.requires("fmilibrary/[~2.3]")
         self.requires("libcbor/0.11.0")
         self.requires("libzip/[~1.11]")
         self.requires("ms-gsl/[>=3 <5]", transitive_headers=True)
         self.requires("boost/[~1.85]", transitive_headers=True, transitive_libs=True)  # Required by Thrift
         if self.options.proxyfmu:
-            self.requires("proxyfmu/0.4.1@osp/stable",
+            self.requires("proxyfmu/0.4.2@osp/stable",
                           transitive_headers=True,
                           transitive_libs=True)
-        self.requires("yaml-cpp/[~0.8]")
+        self.requires("yaml-cpp/[~0.9]")
         self.requires("xerces-c/[~3.2]")
 
     # Exports
@@ -127,3 +127,4 @@ def _is_tests_enabled(self):
             "true",
             "1",
         )
+
diff --git a/src/cosim/observer/file_observer.cpp b/src/cosim/observer/file_observer.cpp
index 73d912df..14a2224e 100644
--- a/src/cosim/observer/file_observer.cpp
+++ b/src/cosim/observer/file_observer.cpp
@@ -217,7 +217,7 @@ class file_observer::slave_value_writer
 
         if (fsw_.fail()) {
             std::stringstream error;
-            error << "Failed to open log file stream: " << filePath.c_str();
+            error << "Failed to open log file stream: " << filePath.string();
             throw std::runtime_error(error.str());
         }
 
@@ -279,7 +279,7 @@ class file_observer::slave_value_writer
 
         if (fsw_.fail()) {
             std::stringstream error;
-            error << "Failed to open log metadata file stream: " << filePath.c_str();
+            error << "Failed to open log metadata file stream: " << filePath.string();
             throw std::runtime_error(error.str());
         }