diff --git a/CMakeLists.txt b/CMakeLists.txt
index 227b970..d738c73 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,6 +20,8 @@ add_library(ds3231 INTERFACE)
 target_include_directories(ds3231 INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include)
 target_link_libraries(ds3231 INTERFACE libavr)
 
+include(${LIBAVR_ROOT}/cmake/checks.cmake)
+
 if(PROJECT_IS_TOP_LEVEL)
 	add_subdirectory(example)
 	enable_testing()
diff --git a/libavr b/libavr
index 99434fb..1412b71 160000
--- a/libavr
+++ b/libavr
@@ -1 +1 @@
-Subproject commit 99434fb29af18f219ba9d24ba22d4d068e5790bb
+Subproject commit 1412b7173b5c343d225cced990473f5e6b510c32
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 0e0d797..373b8b6 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,3 +1,5 @@
+libavr_format_test()
+
 # The battery is a compile: a static_assert that fails is the failure. It is a
 # target rather than only a ctest so a plain build catches a regression too.
 add_library(consteval_tests OBJECT consteval.cpp)
diff --git a/test/consteval.cpp b/test/consteval.cpp
index 0541b51..64b1f9a 100644
--- a/test/consteval.cpp
+++ b/test/consteval.cpp
@@ -37,11 +37,11 @@ static_assert(bcd_round_trips());
 static_assert(hours_from_reg(to_bcd(0)) == 0);   // 24-hour midnight
 static_assert(hours_from_reg(to_bcd(13)) == 13); // 24-hour afternoon
 static_assert(hours_from_reg(to_bcd(23)) == 23);
-static_assert(hours_from_reg(0x40 | to_bcd(12)) == 0);          // 12 AM
-static_assert(hours_from_reg(0x40 | 0x20 | to_bcd(12)) == 12);  // 12 PM
-static_assert(hours_from_reg(0x40 | to_bcd(1)) == 1);           // 1 AM
-static_assert(hours_from_reg(0x40 | 0x20 | to_bcd(1)) == 13);   // 1 PM
-static_assert(hours_from_reg(0x40 | 0x20 | to_bcd(11)) == 23);  // 11 PM
+static_assert(hours_from_reg(0x40 | to_bcd(12)) == 0);         // 12 AM
+static_assert(hours_from_reg(0x40 | 0x20 | to_bcd(12)) == 12); // 12 PM
+static_assert(hours_from_reg(0x40 | to_bcd(1)) == 1);          // 1 AM
+static_assert(hours_from_reg(0x40 | 0x20 | to_bcd(1)) == 13);  // 1 PM
+static_assert(hours_from_reg(0x40 | 0x20 | to_bcd(11)) == 23); // 11 PM
 
 // Sakamoto's method, against dates a calendar can be checked against rather
 // than against this implementation run twice. Sunday is 1.