diff --git a/src/AbstractDiskWriter.cc b/src/AbstractDiskWriter.cc
index a8a7f931..d7a6641a 100644
--- a/src/AbstractDiskWriter.cc
+++ b/src/AbstractDiskWriter.cc
@@ -134,7 +134,7 @@ void AbstractDiskWriter::openFile(int64_t totalLength)
 
 void AbstractDiskWriter::closeFile()
 {
-#if defined HAVE_MMAP || defined __MINGW32__
+#if defined(HAVE_MMAP) || defined(__MINGW32__)
   if(mapaddr_) {
     int errNum = 0;
 #ifdef __MINGW32__
@@ -336,7 +336,7 @@ void AbstractDiskWriter::seek(int64_t offset)
 
 void AbstractDiskWriter::ensureMmapWrite(size_t len, int64_t offset)
 {
-#if defined HAVE_MMAP || defined __MINGW32__
+#if defined(HAVE_MMAP) || defined(__MINGW32__)
   if(enableMmap_) {
     if(mapaddr_) {
       if(static_cast<int64_t>(len + offset) > maplen_) {
diff --git a/src/AsyncNameResolver.cc b/src/AsyncNameResolver.cc
index d9c73062..6dab3c11 100644
--- a/src/AsyncNameResolver.cc
+++ b/src/AsyncNameResolver.cc
@@ -76,7 +76,7 @@ AsyncNameResolver::AsyncNameResolver
 {
   // TODO evaluate return value
   ares_init(&channel_);
-#if defined HAVE_ARES_SET_SERVERS && HAVE_ARES_ADDR_NODE
+#if defined(HAVE_ARES_SET_SERVERS) && defined(HAVE_ARES_ADDR_NODE)
   if(servers) {
     // ares_set_servers has been added since c-ares 1.7.1
     if(ares_set_servers(channel_, servers) != ARES_SUCCESS) {
diff --git a/src/Context.cc b/src/Context.cc
index 4919a378..d0b67d18 100644
--- a/src/Context.cc
+++ b/src/Context.cc
@@ -109,7 +109,7 @@ void showMetalinkFile
 } // namespace
 #endif // ENABLE_METALINK
 
-#if defined ENABLE_BITTORRENT || defined ENABLE_METALINK
+#if defined(ENABLE_BITTORRENT) || defined(ENABLE_METALINK)
 namespace {
 void showFiles
 (const std::vector<std::string>& uris, const std::shared_ptr<Option>& op)
@@ -221,7 +221,7 @@ Context::Context(bool standalone,
         } else {
           createRequestGroupForUriList(requestGroups, op);
         }
-#if defined ENABLE_BITTORRENT || defined ENABLE_METALINK
+#if defined(ENABLE_BITTORRENT) || defined(ENABLE_METALINK)
       } else if(op->get(PREF_SHOW_FILES) == A2_V_TRUE) {
         showFiles(args, op);
         return;
diff --git a/src/File.cc b/src/File.cc
index ca3caf3a..b8bc1d90 100644
--- a/src/File.cc
+++ b/src/File.cc
@@ -250,7 +250,7 @@ bool File::renameTo(const std::string& dest)
 
 bool File::utime(const Time& actime, const Time& modtime) const
 {
-#if defined HAVE_UTIMES && !(defined __MINGW32__)
+#if defined(HAVE_UTIMES) && !defined(__MINGW32__)
   struct timeval times[2] = {
     { actime.getTime(), 0 },
     { modtime.getTime(), 0 }
diff --git a/src/OptionHandlerFactory.cc b/src/OptionHandlerFactory.cc
index ab236886..71c760ff 100644
--- a/src/OptionHandlerFactory.cc
+++ b/src/OptionHandlerFactory.cc
@@ -107,7 +107,7 @@ std::vector<OptionHandler*> OptionHandlerFactory::createOptionHandlers()
     op->setChangeOptionForReserved(true);
     handlers.push_back(op);
   }
-#if defined HAVE_ARES_SET_SERVERS && HAVE_ARES_ADDR_NODE
+#if defined(HAVE_ARES_SET_SERVERS) && defined(HAVE_ARES_ADDR_NODE)
   {
     OptionHandler* op(new DefaultOptionHandler
                       (PREF_ASYNC_DNS_SERVER,
@@ -305,7 +305,7 @@ std::vector<OptionHandler*> OptionHandlerFactory::createOptionHandlers()
     handlers.push_back(op);
   }
 #endif // ENABLE_ASYNC_DNS
-#if defined HAVE_MMAP || defined __MINGW32__
+#if defined(HAVE_MMAP) || defined(__MINGW32__)
   {
     OptionHandler* op(new BooleanOptionHandler
                       (PREF_ENABLE_MMAP,
@@ -1607,7 +1607,7 @@ std::vector<OptionHandler*> OptionHandlerFactory::createOptionHandlers()
     handlers.push_back(op);
   }
   // BitTorrent/Metalink Options
-#if defined ENABLE_BITTORRENT || defined ENABLE_METALINK
+#if defined(ENABLE_BITTORRENT) || defined(ENABLE_METALINK)
   {
     OptionHandler* op(new IntegerRangeOptionHandler
                       (PREF_SELECT_FILE,
diff --git a/src/download_helper.cc b/src/download_helper.cc
index f38f8fa4..e4c2c6f0 100644
--- a/src/download_helper.cc
+++ b/src/download_helper.cc
@@ -161,7 +161,7 @@ std::shared_ptr<RequestGroup> createRequestGroup
 }
 } // namespace
 
-#if defined ENABLE_BITTORRENT || ENABLE_METALINK
+#if defined(ENABLE_BITTORRENT) || defined(ENABLE_METALINK)
 namespace {
 std::shared_ptr<MetadataInfo> createMetadataInfo
 (const std::shared_ptr<GroupId>& gid, const std::string& uri)
diff --git a/test/MetalinkEntryTest.cc b/test/MetalinkEntryTest.cc
index 27122d56..8e47e5c8 100644
--- a/test/MetalinkEntryTest.cc
+++ b/test/MetalinkEntryTest.cc
@@ -74,9 +74,9 @@ void MetalinkEntryTest::testDropUnsupportedResource()
   auto entry = createTestEntry();
 
   entry->dropUnsupportedResource();
-#if defined ENABLE_SSL && defined ENABLE_BITTORRENT
+#if defined(ENABLE_SSL) && defined(ENABLE_BITTORRENT)
   CPPUNIT_ASSERT_EQUAL((size_t)4, entry->resources.size());
-#elif defined ENABLE_SSL || defined ENABLE_BITTORRENT
+#elif defined(ENABLE_SSL) || defined(ENABLE_BITTORRENT)
   CPPUNIT_ASSERT_EQUAL((size_t)3, entry->resources.size());
 #else
   CPPUNIT_ASSERT_EQUAL((size_t)2, entry->resources.size());