diff --git a/src/libbitdht.pro b/src/libbitdht.pro
index cb2f3b4..cb96208 100644
--- a/src/libbitdht.pro
+++ b/src/libbitdht.pro
@@ -66,6 +66,16 @@ win32 {
 		# Switch on extra warnings
 		QMAKE_CFLAGS += -Wextra
 		QMAKE_CXXFLAGS += -Wextra
+
+		# Switch off optimization for release version
+		QMAKE_CXXFLAGS_RELEASE -= -O2
+		QMAKE_CXXFLAGS_RELEASE += -O0
+		QMAKE_CFLAGS_RELEASE -= -O2
+		QMAKE_CFLAGS_RELEASE += -O0
+
+		# Switch on optimization for debug version
+		#QMAKE_CXXFLAGS_DEBUG += -O2
+		#QMAKE_CFLAGS_DEBUG += -O2
 }
 
 ################################# MacOSX ##########################################