diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -16,6 +16,25 @@
 option(BUILD_BITCOIN_TX "Build bitcoin-tx" ON)
 option(BUILD_BITCOIN_QT "Build bitcoin-qt" ON)
 
+# Cmake uses the CMAKE_BUILD_TYPE variable to select the build configuration.
+# By default it supports more configurations that needed for Bitcoin ABC, and
+# all the releases types set NDEBUG which is unwanted as it disables the assert
+# completely.
+# We redefine here the flags to suite our needs, by overriding the built-in
+# RelWithDebInfo configuration (release with debug info).
+
+# RelWithDebInfo CFLAGS are set to -g -O2
+set(RELWITHDEBINFO_G_C_FLAG "-g")
+set(RELWITHDEBINFO_O_C_FLAG "-O2")
+
+# RelWithDebInfo CXXFLAGS flags are set to -g -O2
+set(RELWITHDEBINFO_G_CXX_FLAG "-g")
+set(RELWITHDEBINFO_O_CXX_FLAG "-O2")
+set(CMAKE_C_FLAGS_RELWITHDEBINFO
+	"${RELWITHDEBINFO_G_C_FLAG} ${RELWITHDEBINFO_O_C_FLAG}")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO
+	"${RELWITHDEBINFO_G_CXX_FLAG} ${RELWITHDEBINFO_O_CXX_FLAG}")
+
 # Ensure that WINDRES_PREPROC is enabled when using windres.
 if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
 	list(APPEND CMAKE_RC_FLAGS "-DWINDRES_PREPROC")