diff --git a/cmake/Modules/FindDOOCS.cmake b/cmake/Modules/FindDOOCS.cmake
index de99e1d5c56b88a516686718cb27d950dd4fc80c..65608bd7fe9f69a47c3498f28b024cbed9c65d18 100644
--- a/cmake/Modules/FindDOOCS.cmake
+++ b/cmake/Modules/FindDOOCS.cmake
@@ -45,16 +45,18 @@ set(DOOCS_noAsNeededFlag 1)
 # note, helper functions and variables should also be prefixed with DOOCS_, since everything is exported to
 #  project calling find_package(DOOCS)
 
-function (DOOCS_addToPkgConfPath newPath)
+function (DOOCS_prependToPkgConfPath newPath)
     if (NOT (":$ENV{PKG_CONFIG_PATH}:" MATCHES ":${newPath}:"))
-        set(ENV{PKG_CONFIG_PATH} $ENV{PKG_CONFIG_PATH}:${newPath})
+        set(ENV{PKG_CONFIG_PATH} ${newPath}:$ENV{PKG_CONFIG_PATH})
     endif()
 endfunction()
 
+DOOCS_prependToPkgConfPath(/export/doocs/lib/pkgconfig)
 if(DOOCS_DIR)
-    DOOCS_addToPkgConfPath(${DOOCS_DIR}/pkgconfig)
+    # prepend pkgconfig for user-set doocs dir; this makes sure system-installed DOOCS is overwritten
+    DOOCS_prependToPkgConfPath(${DOOCS_DIR}/x86_64-linux-gnu/pkgconfig)
+    DOOCS_prependToPkgConfPath(${DOOCS_DIR}/pkgconfig)
 endif()
-DOOCS_addToPkgConfPath(/export/doocs/lib/pkgconfig)
 if (NOT DOOCS_FIND_QUIETLY)
     message("FindDOOCS: Using PKG_CONFIG_PATH=$ENV{PKG_CONFIG_PATH}")
 endif()
diff --git a/cmake/set_default_flags.cmake b/cmake/set_default_flags.cmake
index ac0ca3f0a4a5960e023323511faa10354e51c4e9..653cbe98516d6e65e80f51383d1bd9bc11efc406 100644
--- a/cmake/set_default_flags.cmake
+++ b/cmake/set_default_flags.cmake
@@ -31,6 +31,8 @@ set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -O0")
 set(CMAKE_CXX_FLAGS_TSAN "${CMAKE_CXX_FLAGS} -g -O1 -fsanitize=thread -fno-inline")
 set(CMAKE_CXX_FLAGS_ASAN "${CMAKE_CXX_FLAGS} -g -O0 -fsanitize=address -fsanitize=undefined -fsanitize=leak")
 
+add_compile_definitions("$<$<CONFIG:Debug>:_GLIBCXX_ASSERTIONS>")
+
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${${PROJECT_NAME}_C_FLAGS} -Wall -Wextra -Wshadow -pedantic -Wuninitialized")
 set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O3")
 set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -O3 -g")