Index: src/runtime/private.h
==================================================================
--- src/runtime/private.h
+++ src/runtime/private.h
@@ -217,64 +217,77 @@
 		IMP _Nullable buckets[256];
 #endif
 	} *_Nonnull buckets[256];
 };
 
-extern void objc_registerAllCategories(struct objc_symtab *_Nonnull);
+extern void objc_registerAllCategories(struct objc_symtab *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
 extern struct objc_category *_Nullable *_Nullable
-    objc_categoriesForClass(Class _Nonnull);
-extern void objc_unregisterAllCategories(void);
-extern void objc_initializeClass(Class _Nonnull);
-extern void objc_updateDTable(Class _Nonnull);
-extern void objc_registerAllClasses(struct objc_symtab *_Nonnull);
-extern Class _Nullable objc_classnameToClass(const char *_Nonnull, bool);
-extern void objc_unregisterClass(Class _Nonnull);
-extern void objc_unregisterAllClasses(void);
-extern uint32_t objc_string_hash(const void *_Nonnull);
-extern bool objc_string_equal(const void *_Nonnull, const void *_Nonnull);
+    objc_categoriesForClass(Class _Nonnull) OF_VISIBILITY_HIDDEN;
+extern void objc_unregisterAllCategories(void) OF_VISIBILITY_HIDDEN;
+extern void objc_initializeClass(Class _Nonnull) OF_VISIBILITY_HIDDEN;
+extern void objc_updateDTable(Class _Nonnull) OF_VISIBILITY_HIDDEN;
+extern void objc_registerAllClasses(struct objc_symtab *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
+extern Class _Nullable objc_classnameToClass(const char *_Nonnull, bool)
+    OF_VISIBILITY_HIDDEN;
+extern void objc_unregisterClass(Class _Nonnull) OF_VISIBILITY_HIDDEN;
+extern void objc_unregisterAllClasses(void) OF_VISIBILITY_HIDDEN;
+extern uint32_t objc_string_hash(const void *_Nonnull) OF_VISIBILITY_HIDDEN;
+extern bool objc_string_equal(const void *_Nonnull, const void *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
 extern struct objc_hashtable *_Nonnull objc_hashtable_new(
-    objc_hashtable_hash_func, objc_hashtable_equal_func, uint32_t);
-extern struct objc_hashtable_bucket objc_deletedBucket;
+    objc_hashtable_hash_func, objc_hashtable_equal_func, uint32_t)
+    OF_VISIBILITY_HIDDEN;
+extern struct objc_hashtable_bucket objc_deletedBucket OF_VISIBILITY_HIDDEN;
 extern void objc_hashtable_set(struct objc_hashtable *_Nonnull,
-    const void *_Nonnull, const void *_Nonnull);
+    const void *_Nonnull, const void *_Nonnull) OF_VISIBILITY_HIDDEN;
 extern void *_Nullable objc_hashtable_get(struct objc_hashtable *_Nonnull,
-    const void *_Nonnull);
+    const void *_Nonnull) OF_VISIBILITY_HIDDEN;
 extern void objc_hashtable_delete(struct objc_hashtable *_Nonnull,
-    const void *_Nonnull);
-extern void objc_hashtable_free(struct objc_hashtable *_Nonnull);
-extern void objc_registerSelector(struct objc_selector *_Nonnull);
-extern void objc_registerAllSelectors(struct objc_symtab *_Nonnull);
-extern void objc_unregisterAllSelectors(void);
-extern struct objc_sparsearray *_Nonnull objc_sparsearray_new(uint8_t);
+    const void *_Nonnull) OF_VISIBILITY_HIDDEN;
+extern void objc_hashtable_free(struct objc_hashtable *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
+extern void objc_registerSelector(struct objc_selector *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
+extern void objc_registerAllSelectors(struct objc_symtab *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
+extern void objc_unregisterAllSelectors(void) OF_VISIBILITY_HIDDEN;
+extern struct objc_sparsearray *_Nonnull objc_sparsearray_new(uint8_t)
+    OF_VISIBILITY_HIDDEN;
 extern void *_Nullable objc_sparsearray_get(struct objc_sparsearray *_Nonnull,
-    uintptr_t);
+    uintptr_t) OF_VISIBILITY_HIDDEN;
 extern void objc_sparsearray_set(struct objc_sparsearray *_Nonnull, uintptr_t,
-    void *_Nullable);
-extern void objc_sparsearray_free(struct objc_sparsearray *_Nonnull);
-extern struct objc_dtable *_Nonnull objc_dtable_new(void);
+    void *_Nullable) OF_VISIBILITY_HIDDEN;
+extern void objc_sparsearray_free(struct objc_sparsearray *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
+extern struct objc_dtable *_Nonnull objc_dtable_new(void) OF_VISIBILITY_HIDDEN;
 extern void objc_dtable_copy(struct objc_dtable *_Nonnull,
-    struct objc_dtable *_Nonnull);
+    struct objc_dtable *_Nonnull) OF_VISIBILITY_HIDDEN;
 extern void objc_dtable_set(struct objc_dtable *_Nonnull, uint32_t,
-    IMP _Nullable);
-extern void objc_dtable_free(struct objc_dtable *_Nonnull);
-extern void objc_dtable_cleanup(void);
-extern void objc_initStaticInstances(struct objc_symtab *_Nonnull);
-extern void objc_forgetPendingStaticInstances(void);
-extern void objc_zeroWeakReferences(id _Nonnull);
-extern Class _Nullable object_getTaggedPointerClass(id _Nonnull);
+    IMP _Nullable) OF_VISIBILITY_HIDDEN;
+extern void objc_dtable_free(struct objc_dtable *_Nonnull) OF_VISIBILITY_HIDDEN;
+extern void objc_dtable_cleanup(void) OF_VISIBILITY_HIDDEN;
+extern void objc_initStaticInstances(struct objc_symtab *_Nonnull)
+    OF_VISIBILITY_HIDDEN;
+extern void objc_forgetPendingStaticInstances(void) OF_VISIBILITY_HIDDEN;
+extern void objc_zeroWeakReferences(id _Nonnull) OF_VISIBILITY_HIDDEN;
+extern Class _Nullable object_getTaggedPointerClass(id _Nonnull)
+    OF_VISIBILITY_HIDDEN;
 #ifdef OF_HAVE_THREADS
-extern void objc_globalMutex_lock(void);
-extern void objc_globalMutex_unlock(void);
-extern void objc_globalMutex_free(void);
+extern void objc_globalMutex_lock(void) OF_VISIBILITY_HIDDEN;
+extern void objc_globalMutex_unlock(void) OF_VISIBILITY_HIDDEN;
+extern void objc_globalMutex_free(void) OF_VISIBILITY_HIDDEN;
 #else
 # define objc_globalMutex_lock()
 # define objc_globalMutex_unlock()
 # define objc_globalMutex_free()
 #endif
-extern char *_Nullable objc_strdup(const char *_Nonnull string);
+extern char *_Nullable objc_strdup(const char *_Nonnull string)
+    OF_VISIBILITY_HIDDEN;
 
-static inline IMP _Nullable
+static OF_INLINE IMP _Nullable
 objc_dtable_get(const struct objc_dtable *_Nonnull dtable, uint32_t idx)
 {
 #ifdef OF_SELUID24
 	uint8_t i = idx >> 16;
 	uint8_t j = idx >> 8;
@@ -288,11 +301,11 @@
 	return dtable->buckets[i]->buckets[j];
 #endif
 }
 
 extern void OF_NO_RETURN_FUNC objc_error(const char *_Nonnull title,
-    const char *_Nonnull format, ...);
+    const char *_Nonnull format, ...) OF_VISIBILITY_HIDDEN;
 #define OBJC_ERROR(...)							\
 	objc_error("ObjFWRT @ " __FILE__ ":" OF_STRINGIFY(__LINE__),	\
 	    __VA_ARGS__)
 
 #if defined(OF_ELF)

Index: tests/plugin/TestPlugin.m
==================================================================
--- tests/plugin/TestPlugin.m
+++ tests/plugin/TestPlugin.m
@@ -19,30 +19,10 @@
 
 #include "config.h"
 
 #import "TestPlugin.h"
 
-#ifdef OF_OBJFW_RUNTIME
-# import "runtime/private.h"
-
-OF_DESTRUCTOR()
-{
-	Class class = objc_getClass("TestPlugin");
-
-	if (class == Nil)
-		/*
-		 * musl has broken dlclose(): Instead of calling the destructor
-		 * on dlclose(), they call it on exit(). This of course means
-                 * that our tests might have already called objc_deinit() and
-                 * the class is already gone.
-		 */
-		return;
-
-	objc_unregisterClass(class);
-}
-#endif
-
 @implementation TestPlugin
 - (int)test: (int)num
 {
 	return num * 2;
 }