Index: src/Concurrency/Keywords.cc
===================================================================
--- src/Concurrency/Keywords.cc	(revision ceedde6025cceafa3bb88869c460143c276914fa)
+++ src/Concurrency/Keywords.cc	(revision 2e0285177bb7e5cdc2afd200e041b827f132f1a3)
@@ -501,13 +501,13 @@
 	void MutexKeyword::postvisit(StructDecl* decl) {
 
-		if( decl->name == "monitor_desc" ) {
+		if( decl->name == "monitor_desc" && decl->body ) {
 			assert( !monitor_decl );
 			monitor_decl = decl;
 		}
-		else if( decl->name == "monitor_guard_t" ) {
+		else if( decl->name == "monitor_guard_t" && decl->body ) {
 			assert( !guard_decl );
 			guard_decl = decl;
 		}
-		else if( decl->name == "monitor_dtor_guard_t" ) {
+		else if( decl->name == "monitor_dtor_guard_t" && decl->body ) {
 			assert( !dtor_guard_decl );
 			dtor_guard_decl = decl;