diff --git a/tests/auto/tst_io.cpp b/tests/auto/tst_io.cpp
index 48abda6..fd31b31 100644
--- a/tests/auto/tst_io.cpp
+++ b/tests/auto/tst_io.cpp
@@ -27,6 +27,11 @@
 
 using namespace std;
 
+constexpr uint64_t operator""_u64(unsigned long long v)
+{
+    return static_cast<uint64_t>(v);
+}
+
 TEST_CASE ("write data", "[write]") {
     TempFile file;
     REQUIRE(file.open());
@@ -124,7 +129,7 @@ TEST_CASE ("read line 64bit", "[read]") {
     REQUIRE(reader >> module);
     REQUIRE(module == "/tmp/KDevelop-5.2.1-x86_64/usr/lib/libKF5Completion.so.5");
 
-    for (uint64_t expected : {0x7f48beedc00ul, 0x0ul, 0x36854ul, 0x236858ul, 0x2700ul}) {
+    for (auto expected : {0x7f48beedc00_u64, 0x0_u64, 0x36854_u64, 0x236858_u64, 0x2700_u64}) {
         uint64_t addr = 0;
         REQUIRE(reader >> addr);
         REQUIRE(addr == expected);
diff --git a/src/util/linewriter.h b/src/util/linewriter.h
index 73a7930..e895e87 100644
--- a/src/util/linewriter.h
+++ b/src/util/linewriter.h
@@ -158,6 +158,11 @@ public:
         return __builtin_clzl(V);
     }

+    inline static unsigned clz(long long unsigned V)
+    {
+        return __builtin_clzll(V);
+    }
+
     template <typename V>
     static char* writeHexNumber(char* buffer, V value)
     {