diff --git a/.gitmodules b/.gitmodules
index 51341cc..fceb099 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -2,3 +2,6 @@
 	path = testscpp/Catch2
 	url = https://github.com/catchorg/Catch2.git
 	branch = v2.x
+[submodule "extern/spdlog"]
+	path = extern/spdlog
+	url = https://github.com/gabime/spdlog.git
diff --git a/MANIFEST.in b/MANIFEST.in
index e7418e2..c3defa4 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,3 +1,5 @@
 include pyproject.toml
 recursive-include dwave/preprocessing/include/ *.hpp *.h
 recursive-include dwave/preprocessing *.pyx *.pxd *.pyx.src
+graft extern/spdlog/include/
+include extern/spdlog/LICENSE
diff --git a/dwave/preprocessing/include/dwave/presolve.h b/dwave/preprocessing/include/dwave/presolve.h
index d6d63c1..08f4c7b 100644
--- a/dwave/preprocessing/include/dwave/presolve.h
+++ b/dwave/preprocessing/include/dwave/presolve.h
@@ -19,6 +19,7 @@
 #include <utility>
 #include <vector>
 
+#include "spdlog/spdlog.h"
 #include "dimod/constrained_quadratic_model.h"
 
 namespace dwave {
diff --git a/extern/spdlog b/extern/spdlog
new file mode 160000
index 0000000..ad0e89c
--- /dev/null
+++ b/extern/spdlog
@@ -0,0 +1 @@
+Subproject commit ad0e89cbfb4d0c1ce4d097e134eb7be67baebb36
diff --git a/setup.py b/setup.py
index 4ea96c4..be30156 100644
--- a/setup.py
+++ b/setup.py
@@ -62,6 +62,7 @@ def build_extensions(self):
     include_dirs=[
         numpy.get_include(),
         dimod.get_include(),
+        'extern/spdlog/include/',
         ],
     install_requires=[
         'numpy>=1.20.0,<2.0.0',  # keep synced with circle-ci, pyproject.toml
diff --git a/testscpp/Makefile b/testscpp/Makefile
index a565fe2..b22be20 100644
--- a/testscpp/Makefile
+++ b/testscpp/Makefile
@@ -1,11 +1,12 @@
-ROOT := ../
+ROOT := ..
 SRC := $(ROOT)/dwave/preprocessing/
 CATCH2 := $(ROOT)/testscpp/Catch2/single_include/
 DIMOD := $(shell python -c 'import dimod; print(dimod.get_include())')
-INCLUDES := -I $(SRC)/include/ -I $(DIMOD) -I $(CATCH2)
+SPDLOG := $(ROOT)/extern/spdlog/include/
+INCLUDES := -I $(SRC)/include/ -I $(DIMOD) -I $(CATCH2) -I $(SPDLOG)
 FLAGS := -std=c++17 -Wall -Wno-unknown-pragmas -Wno-sign-compare -Wno-deprecated-declarations -fcompare-debug-second -O3 
 
-all: catch2 test_main test_main_parallel tests tests_parallel
+all: update test_main test_main_parallel tests tests_parallel
 
 tests: test_main.out
 	./test_main 
@@ -16,11 +17,12 @@ tests_parallel: test_main_parallel.out
 test_main: test_main.cpp
 	g++ $(FLAGS) -c test_main.cpp
 	g++ $(FLAGS) test_main.o tests/*.cpp -o test_main $(INCLUDES)
+
 test_main_parallel: test_main.cpp
 	g++ $(FLAGS) -fopenmp -c test_main.cpp -o test_main_parallel.o
 	g++ $(FLAGS) -fopenmp test_main_parallel.o tests/*.cpp -o test_main_parallel $(INCLUDES)
 
-catch2:
+update:
 	git submodule init
 	git submodule update