diff --git a/CMakeLists.txt b/CMakeLists.txt
index d1055456b..1c3780bf3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -138,6 +138,11 @@ if(NOT HAVE_COUNTER_MACRO AND ICINGA2_UNITY_BUILD)
   set(ICINGA2_UNITY_BUILD FALSE)
 endif()
 
+if(NOT MSVC)
+  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D_DEBUG")
+  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -D_DEBUG")
+endif()
+
 check_function_exists(vfork HAVE_VFORK)
 check_function_exists(backtrace_symbols HAVE_BACKTRACE_SYMBOLS)
 check_function_exists(pipe2 HAVE_PIPE2)
diff --git a/INSTALL.md b/INSTALL.md
index 0ee1f828c..68b064d41 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -138,7 +138,7 @@ variables are supported:
 - `ICINGA2_GROUP`: The group Icinga 2 should run as; defaults to `icinga`
 - `ICINGA2_GIT_VERSION_INFO`: Whether to use Git to determine the version number; defaults to `ON`
 - `ICINGA2_COMMAND_GROUP`: The command group Icinga 2 should use; defaults to `icingacmd`
-- `ICINGA2_UNITY_BUILD`: Whether to perform a unity build
+- `ICINGA2_UNITY_BUILD`: Whether to perform a unity build; defaults to `OFF`
 - `ICINGA2_PLUGINDIR`: The path for the Monitoring Plugins project binaries; defaults to `/usr/lib/nagios/plugins`
 - `ICINGA2_RUNDIR`: The location of the "run" directory; defaults to `CMAKE_INSTALL_LOCALSTATEDIR/run`
 - `CMAKE_INSTALL_SYSCONFDIR`: The configuration directory; defaults to `CMAKE_INSTALL_PREFIX/etc`
diff --git a/icinga-app/icinga.cpp b/icinga-app/icinga.cpp
index e05ee9cf7..14925ec08 100644
--- a/icinga-app/icinga.cpp
+++ b/icinga-app/icinga.cpp
@@ -273,7 +273,11 @@ int Main(void)
 				appName = appName.SubStr(3, appName.GetLength() - 3);
 
 			std::cout << appName << " " << "- The Icinga 2 network monitoring daemon (version: "
-			    << Application::GetVersion() << ")" << std::endl << std::endl;
+			    << Application::GetVersion()
+#ifdef _DEBUG
+			    << "; debug"
+#endif /* _DEBUG */
+			    << ")" << std::endl << std::endl;
 
 			if (!command || vm.count("help")) {
 				std::cout << "Usage:" << std::endl
diff --git a/lib/base/i2-base.hpp b/lib/base/i2-base.hpp
index b837122ce..19f203634 100644
--- a/lib/base/i2-base.hpp
+++ b/lib/base/i2-base.hpp
@@ -56,10 +56,6 @@
 #	pragma warning(disable:4251)
 #	pragma warning(disable:4275)
 #	pragma warning(disable:4345)
-#else /* _MSC_VER */
-#	ifndef NDEBUG
-#		define _DEBUG
-#	endif /* NDEBUG */
 #endif /* _MSC_VER */
 
 #include "config.h"
diff --git a/lib/cli/daemoncommand.cpp b/lib/cli/daemoncommand.cpp
index 77eb811aa..3a58e38d6 100644
--- a/lib/cli/daemoncommand.cpp
+++ b/lib/cli/daemoncommand.cpp
@@ -325,7 +325,11 @@ int DaemonCommand::Run(const po::variables_map& vm, const std::vector<std::strin
 	Application::MakeVariablesConstant();
 
 	Log(LogInformation, "cli")
-	    << "Icinga application loader (version: " << Application::GetVersion() << ")";
+	    << "Icinga application loader (version: " << Application::GetVersion()
+#ifdef _DEBUG
+	    << "; debug"
+#endif /* _DEBUG */
+	    << ")";
 
 	String appType = LoadAppType(Application::GetApplicationType());