diff --git a/src/Mayaqua/CMakeLists.txt b/src/Mayaqua/CMakeLists.txt
index af36a165..ce7aadac 100644
--- a/src/Mayaqua/CMakeLists.txt
+++ b/src/Mayaqua/CMakeLists.txt
@@ -37,6 +37,9 @@ set(CMAKE_REQUIRED_LIBRARIES ${OPENSSL_CRYPTO_LIBRARY})
 
 check_function_exists(EVP_PKEY_get_raw_public_key HAVE_OPENSSL_EVP_PKEY)
 
+unset(CMAKE_REQUIRED_INCLUDES)
+unset(CMAKE_REQUIRED_LIBRARIES)
+
 if(NOT HAVE_OPENSSL_EVP_PKEY)
         message(FATAL_ERROR "required EVP_PKEY_get_raw_public_key() is not found in OpenSSL library")
 endif()