diff --git a/CMakeLists.txt b/CMakeLists.txt
index 422a7c4..7b90993 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,10 +7,10 @@
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2 -Wall -Wextra -W -Wdeclaration-after-statement")
   set(CMAKE_C_FLAGS_DEBUG "-g3 -O0")
   set(CMAKE_C_FLAGS_COVERAGE "-g3 -O0 -fprofile-arcs -ftest-coverage -lgcov")
-  set(CMAKE_C_FLAGS_CHECK "${CMAKE_C_FLAGS} -O2 -Wall -Wextra -W -Wdeclaration-after-statement -Wlogical-op -Wwrite-strings -Wmissing-prototypes -Wmissing-declarations")
-  set(CMAKE_C_FLAGS_CHECKFULL "${CMAKE_C_FLAGS} -O2 -Wall -Wextra -W -Wdeclaration-after-statement -Wlogical-op -Wcast-qual -Wwrite-strings -Wmissing-prototypes -Wmissing-declarations")
+  set(CMAKE_C_FLAGS_CHECK "${CMAKE_C_FLAGS} -Wlogical-op -Wwrite-strings")
+  set(CMAKE_C_FLAGS_CHECKFULL "${CMAKE_C_FLAGS_CHECK} -Wcast-qual")
 endif(CMAKE_COMPILER_IS_GNUCC)
- 
+
 if(CMAKE_BUILD_TYPE STREQUAL "Coverage")
   if(CMAKE_COMPILER_IS_GNUCC)
     set(CMAKE_SHARED_LINKER_FLAGS "-fprofile-arcs -ftest-coverage")
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index c4060d1..1a3e077 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -69,6 +69,11 @@
 set(libs ws2_32)
 endif(WIN32)
 
+if(CMAKE_COMPILER_IS_GNUCC)
+  set(CMAKE_C_FLAGS_CHECK "${CMAKE_C_FLAGS_CHECK} -Wmissing-declarations -Wmissing-prototypes")
+  set(CMAKE_C_FLAGS_CHECKFULL "${CMAKE_C_FLAGS_CHECK} -Wcast-qual")
+endif(CMAKE_COMPILER_IS_GNUCC)
+
 if(NOT USE_SHARED_POLARSSL_LIBRARY)
 
 add_library(polarssl STATIC ${src})