diff --git a/class_table.c b/class_table.c
index cf06e10..372b7a0 100644
--- a/class_table.c
+++ b/class_table.c
@@ -131,7 +131,7 @@ void __objc_init_class_tables(void)
 // Loader functions
 ////////////////////////////////////////////////////////////////////////////////
 
-BOOL  objc_resolve_class(Class cls)
+BOOL objc_resolve_class(Class cls)
 {
 	// Skip this if the class is already resolved.
 	if (objc_test_class_flag(cls, objc_class_flag_resolved)) { return YES; }
diff --git a/selector.h b/selector.h
index 9125f56..c5d7446 100644
--- a/selector.h
+++ b/selector.h
@@ -33,5 +33,14 @@ static uint32_t get_untyped_idx(SEL aSel)
 	return (uint32_t)(uintptr_t)untyped->name;
 }
 
+/**
+ * Returns whether a selector is mapped.  
+ */
+BOOL sel_is_mapped(SEL selector);
+/**
+ * Registers the selector.  This selector may be returned later, so it must not
+ * be freed.
+ */
+SEL objc_register_selector(SEL aSel);
 
 #endif // OBJC_SELECTOR_H_INCLUDED
diff --git a/selector_table.c b/selector_table.c
index 6b6b757..75e3de3 100644
--- a/selector_table.c
+++ b/selector_table.c
@@ -256,7 +256,7 @@ static inline void register_selector_locked(SEL aSel)
 /**
  * Registers a selector.  This assumes that the argument is never deallocated.
  */
-static SEL objc_register_selector(SEL aSel)
+SEL objc_register_selector(SEL aSel)
 {
 	if (isSelRegistered(aSel))
 	{
@@ -486,7 +486,7 @@ SEL sel_register_name(const char *name)
 	return sel_registerName(name);
 }
 
-SEL sel_register_typed_name (const char *name, const char *type)
+SEL sel_register_typed_name(const char *name, const char *type)
 {
 	return sel_registerTypedName_np(name, type);
 }
diff --git a/sendmsg2.c b/sendmsg2.c
index b95d0fe..563b7bb 100644
--- a/sendmsg2.c
+++ b/sendmsg2.c
@@ -35,6 +35,7 @@ Slot_t objc_msg_lookup_internal(id *receiver,
                                 SEL selector, 
                                 id sender)
 {
+retry:;
 	Slot_t result = objc_dtable_lookup((*receiver)->isa->dtable,
 			PTR_TO_IDX(selector->name));
 	if (0 == result)
@@ -56,6 +57,13 @@ Slot_t objc_msg_lookup_internal(id *receiver,
 		}
 		if (0 == result)
 		{
+			if (!sel_is_mapped(selector))
+			{
+				objc_register_selector(selector);
+				// This should be a tail call, but GCC is stupid and won't let
+				// us tail call an always_inline function.
+				goto retry;
+			}
 			if ((result = objc_dtable_lookup(dtable, get_untyped_idx(selector))))
 			{
 				fprintf(stderr, "Calling %s with incorrect signature.  "
@@ -250,6 +258,11 @@ Slot_t objc_get_slot(Class cls, SEL selector)
 		}
 		if (NULL == result)
 		{
+			if (!sel_is_mapped(selector))
+			{
+				objc_register_selector(selector);
+				return objc_get_slot(cls, selector);
+			}
 			if ((result = objc_dtable_lookup(dtable, get_untyped_idx(selector))))
 			{
 				fprintf(stderr, "Calling %s with incorrect signature.  "