diff --git a/externals/CMakeLists.txt b/externals/CMakeLists.txt
index b837bfaded..5935c6f69e 100644
--- a/externals/CMakeLists.txt
+++ b/externals/CMakeLists.txt
@@ -58,7 +58,8 @@ CPMAddPackage(
 )
 
 if (mbedtls_ADDED)
-    target_include_directories(mbedtls PUBLIC ./mbedtls/include)
+    target_include_directories(mbedtls PUBLIC ${mbedtls_SOURCE_DIR}/include)
+
     if (NOT MSVC)
         target_compile_options(mbedcrypto PRIVATE
             -Wno-unused-but-set-variable