diff --git a/src/org/rascalmpl/core/library/lang/rascalcore/check/RascalConfig.rsc b/src/org/rascalmpl/core/library/lang/rascalcore/check/RascalConfig.rsc
index 286205bc..bbc1f23d 100644
--- a/src/org/rascalmpl/core/library/lang/rascalcore/check/RascalConfig.rsc
+++ b/src/org/rascalmpl/core/library/lang/rascalcore/check/RascalConfig.rsc
@@ -463,7 +463,7 @@ loc rascalCreateLogicalLoc(Define def, str _modelName, PathConfig pcfg){
      return def.defined;
 }
 
-@memo
+@memo{expireAfter(minutes=5),maximumSize(1000)}
 rel[str shortName, str longName] getModuleNames(PathConfig pcfg){
     longNames = {};
     for(srcdir <- pcfg.srcs){