diff --git a/recipes/imath/all/conanfile.py b/recipes/imath/all/conanfile.py
index 79c783b58dc0a..ca052909386af 100644
--- a/recipes/imath/all/conanfile.py
+++ b/recipes/imath/all/conanfile.py
@@ -2,6 +2,7 @@
 from conan.tools.build import check_min_cppstd
 from conan.tools.cmake import CMake, CMakeToolchain, cmake_layout
 from conan.tools.files import collect_libs, copy, get, rmdir
+from conan.tools.microsoft import is_msvc
 import os
 
 required_conan_version = ">=1.53.0"
@@ -49,6 +50,10 @@ def source(self):
 
     def generate(self):
         tc = CMakeToolchain(self)
+        if is_msvc(self) and self.settings.compiler.get_safe("cppstd"):
+            # when msvc is working with a C++ standard level higher
+            # than the default, we need the __cplusplus macro to be correct
+            tc.variables["CMAKE_CXX_FLAGS"] = "/Zc:__cplusplus"        
         tc.generate()
 
     def build(self):