diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5b4e2a1c2..2523ecd85 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -66,7 +66,7 @@ ecbuild_info("Operating system=${CMAKE_SYSTEM} (${EC_OS_BITS} bits)")
 # some variables/options of this project
 
 if( CMAKE_CXX_COMPILER_ID STREQUAL "GNU" )
-    ecbuild_add_cxx_flags("-fpermissive -Wno-write-strings -Wno-deprecated -Werror=return-type")
+    ecbuild_add_cxx_flags("-Wno-write-strings -Wno-deprecated")
 elseif (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" OR CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
     ecbuild_add_cxx_flags("-fpermissive -Wno-deprecated -Wno-c++11-compat-deprecated-writable-strings")
 elseif( CMAKE_CXX_COMPILER_ID STREQUAL "Cray" )