diff --git a/test/http/http_body_test.cpp b/test/http/http_body_test.cpp
index d8c9dd1..9a1a098 100644
--- a/test/http/http_body_test.cpp
+++ b/test/http/http_body_test.cpp
@@ -116,7 +116,9 @@
     HttpBody::value_type value(EncodingType::Base64);
     TemporaryFileHandle temporaryFile("teststring");
     boost::system::error_code ec;
-    value.setFd(fileno(fopen(temporaryFile.stringPath.c_str(), "r")), ec);
+    FILE* r = fopen(temporaryFile.stringPath.c_str(), "r");
+    ASSERT_NE(r, nullptr);
+    value.setFd(fileno(r), ec);
     ASSERT_FALSE(ec);
 
     std::array<char, 4096> buffer{};