Index: src/runtime/private.h
==================================================================
--- src/runtime/private.h
+++ src/runtime/private.h
@@ -348,12 +348,12 @@
 
 	return dtable->buckets[i]->buckets[j];
 #endif
 }
 
-extern void OF_NO_RETURN_FUNC objc_error(const char *file, unsigned int line,
-    const char *format, ...);
+extern void OF_NO_RETURN_FUNC objc_error(const char *_Nonnull file,
+    unsigned int line, const char *_Nonnull format, ...);
 #define OBJC_ERROR(...) objc_error(__FILE__, __LINE__, __VA_ARGS__)
 
 #if defined(OF_ELF)
 # if defined(OF_X86_64) || defined(OF_X86) || defined(OF_POWERPC) || \
     defined(OF_ARM64) || defined(OF_ARM) || \