diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp
@@ -24,7 +24,7 @@
 void LibIgnore::AddIgnoredLibrary(const char *name_templ) {
   Lock lock(&mutex_);
   if (count_ >= kMaxLibs) {
-    Report("%s: too many ignored libraries (max: %lu)\n", SanitizerToolName,
+    Report("%s: too many ignored libraries (max: %zu)\n", SanitizerToolName,
            kMaxLibs);
     Die();
   }