diff --git a/src/makefile b/src/makefile
index 30aa89cc4..adfbe7f05 100644
--- a/src/makefile
+++ b/src/makefile
@@ -6,7 +6,7 @@
 # Variables.
 CXX ?= g++
 USE_ROUTING ?= true
-CXXFLAGS = -MMD -MP -I. -std=c++17 -Wextra -Wpedantic -Wall -O3 -DASIO_STANDALONE -DUSE_ROUTING=$(USE_ROUTING)
+CXXFLAGS = -MMD -MP -I. -std=c++17 -Wextra -Wpedantic -Wall -O3 -DASIO_STANDALONE -DUSE_ROUTING=$(USE_ROUTING) -DNDEBUG
 LDLIBS = -lpthread
 
 # Using all cpp files in current directory.