diff --git a/loader.c b/loader.c
index f4df0471..4c9ba39d 100644
--- a/loader.c
+++ b/loader.c
@@ -13,6 +13,10 @@
 #include <stdio.h>
 #include <string.h>
 
+#if defined(__wasm__) && defined(OLDABI_COMPAT)
+#error WebAssembly does not support the legacy Objective-C ABI.
+#endif
+
 /**
  * Runtime lock.  This is exposed in 
  */
@@ -214,7 +218,7 @@ OBJC_PUBLIC void __objc_load(struct objc_init *init)
 		{
 			continue;
 		}
-		objc_register_selector(sel);
+		objc_register_selector_unchecked(sel);
 	}
 	for (struct objc_protocol *proto = init->proto_begin ; proto < init->proto_end ;
 	     proto++)
diff --git a/selector.h b/selector.h
index c9409873..852f2ce7 100644
--- a/selector.h
+++ b/selector.h
@@ -56,6 +56,12 @@ extern "C"
  */
 SEL objc_register_selector(SEL aSel);
 
+/**
+ * Registers a selector that the caller knows has not already been registered.
+ * The version 2 ABI provides each selector exactly once during __objc_load.
+ */
+SEL objc_register_selector_unchecked(SEL aSel);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/selector_table.cc b/selector_table.cc
index 5fc68af8..576a669b 100644
--- a/selector_table.cc
+++ b/selector_table.cc
@@ -437,6 +437,11 @@ extern "C" PRIVATE SEL objc_register_selector(SEL aSel)
 	{
 		return aSel;
 	}
+	return objc_register_selector_unchecked(aSel);
+}
+
+extern "C" PRIVATE SEL objc_register_selector_unchecked(SEL aSel)
+{
 	UnregisteredSelector unregistered{aSel->name, aSel->types};
 	// Check that this isn't already registered, before we try
 	SEL registered = selector_lookup(aSel->name, aSel->types);