diff --git a/rascal-lsp/pom.xml b/rascal-lsp/pom.xml
index 79a3ebb03..d37ea1096 100644
--- a/rascal-lsp/pom.xml
+++ b/rascal-lsp/pom.xml
@@ -64,7 +64,7 @@
     <dependency>
       <groupId>org.rascalmpl</groupId>
       <artifactId>rascal</artifactId>
-      <version>0.43.0-RC7</version>
+      <version>0.43.0-RC8</version>
     </dependency>
     <!-- Rascal tests require JUnit 4 -->
     <dependency>
diff --git a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/Rename.rsc b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/Rename.rsc
index c599b067c..27f2f4c88 100644
--- a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/Rename.rsc
+++ b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/Rename.rsc
@@ -74,17 +74,18 @@ import analysis::diff::edits::AnnotatedTextEdits;
 private bool isQualifiedUse(loc use, Define _:<_, str id, _, _, _, _>) = size(id) != use.length;
 
 void rascalCheckCausesOverlappingDefinitions(set[Define] currentDefs, str newName, Tree tr, TModel tm, Renamer r) {
-    defUse = invert(tm.useDef);
+    useDef = getUseDef(tm);
+    defUse = invert(useDef);
     unescNewName = forceUnescapeNames(newName);
     reachable = rascalGetReflexiveModulePaths(tm).to;
-    usedModules = {d.top | loc d <- tm.useDef<1>};
+    usedModules = {d.top | loc d <- useDef<1>};
     usedModels = (m: tm | loc m <- usedModules, TModel tm := r.getConfig().tmodelForLoc(m)) + (tr.src.top: tm);
     newNameDefs = {nD | TModel tm <- range(usedModels), Define nD:<_, unescNewName, _, _, _, _> <- tm.defines};
     curAndNewDefinitions = (d.defined: d | d <- currentDefs + newNameDefs); // temporary map for overloading checks
     maybeImplicitDefs = {n.names[-1].src | /QualifiedName n := tr};
 
     bool isImplicitDef(Define d)
-        = (d.idRole is variableId && d.defined in tm.useDef<0>) // variable that's both a use and a def
+        = (d.idRole is variableId && d.defined in useDef<0>) // variable that's both a use and a def
         || (d.idRole is patternVariableId && d.defined in maybeImplicitDefs) // or pattern variable without a type
         ;
 
@@ -304,7 +305,7 @@ private set[Define] tryGetCursorDefinitions(list[Tree] cursor, TModel(loc) getMo
         if (tm.definitions[c.src]?) {
             // Cursor at definition
             cursorDefs = {tm.definitions[c.src]};
-        } else if (defs: {_, *_} := tm.useDef[c.src]) {
+        } else if (defs: {_, *_} := getUseDef(tm)[c.src]) {
             // Cursor at use
             cursorDefs = flatMapPerFile(defs, set[Define](loc f, set[loc] localDefs) {
                 localTm = f.top == cursorLoc.top ? tm : getModel(f);
@@ -404,7 +405,7 @@ void renameUses(set[Define] defs, str newName, TModel tm, Renamer r) {
     tm = getConditionallyAugmentedTModel(getModuleScopes(tm)[tm.modelName].top, defs, {augmentUses()}, r);
 
     definitions = {<d.defined, d> | d <- defs};
-    useDefs = toMap(tm.useDef o definitions);
+    useDefs = toMap(getUseDef(tm) o definitions);
     for (loc u <- useDefs) {
         if (set[Define] ds:{_, *_} := useDefs[u], u notin defs.defined) {
             r.textEdit(replace(nameSuffix(u, ds, r), escName));
diff --git a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Common.rsc b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Common.rsc
index be57c2e14..bea5292e6 100644
--- a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Common.rsc
+++ b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Common.rsc
@@ -68,6 +68,17 @@ bool isContainedInScope(loc l, loc scope, TModel tm) {
 
 loc getModuleFile(TModel tm) = getModuleScopes(tm)[tm.modelName].top;
 
+@synopsis{
+    Gets the use-def relation of TModel `tm`. Unlike `tm.useDef`, this function
+    guarantees that the range of the relation is a subset of the domain of
+    `tm.definitions`. Thus, unlike pairs in `tm.useDef`, if `<u, d>` is a pair
+    in the relation, then `d` can safely be used to index `tm.definitions`.
+}
+rel[loc, loc] getUseDef(TModel tm) {
+    map[loc, loc] id2define = invertUnique(tm.define2id);
+    return {<u, id2define[d] ? d> | <loc u, loc d> <- tm.useDef};
+}
+
 private set[str] reservedNames = getRascalReservedIdentifiers();
 
 str forceUnescapeNames(str name) = replaceAll(name, "\\", "");
diff --git a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Fields.rsc b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Fields.rsc
index af6fc60e6..e2a9c707a 100644
--- a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Fields.rsc
+++ b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Fields.rsc
@@ -79,7 +79,7 @@ set[Define] getFieldDefinitions(set[AType] containerTypes, str fieldName, TModel
 
 @synopsis{Collect all definitions for the field <fieldName> in ADT/collection/tuple by tree.}
 set[Define] getFieldDefinitions(Tree container, str fieldName, TModel tm, TModel(loc) getModel) {
-    if (defs:{_, *_} := tm.useDef[container.src]) {
+    if (defs:{_, *_} := getUseDef(tm)[container.src]) {
         return flatMapPerFile(defs, set[Define](loc f, set[loc] localContainerDefs) {
             fileTm = getModel(f);
 
diff --git a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Modules.rsc b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Modules.rsc
index 12eafe3f1..77733e74a 100644
--- a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Modules.rsc
+++ b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Modules.rsc
@@ -136,8 +136,9 @@ void renameDefinitionUnchecked(Define d:<_, currentName, _, moduleId(), _, _>, l
 void renameAdditionalUses(set[Define] _:{<_, str moduleName, _, moduleId(), loc modDef, _>}, str newName, TModel tm, Renamer r) {
     // We get the module location from the uses. If there are no uses, this is skipped.
     // That's intended, since this function is only supposed to rename uses.
-    if ({loc u, *_} := tm.useDef<0>) {
-        for (/QualifiedName qn := r.getConfig().parseLoc(u.top), any(d <- tm.useDef[qn.src], d.top == modDef.top),
+    rel[loc, loc] useDef = getUseDef(tm);
+    if ({loc u, *_} := useDef<0>) {
+        for (/QualifiedName qn := r.getConfig().parseLoc(u.top), any(d <- useDef[qn.src], d.top == modDef.top),
             just(<moduleName, prefLoc>) := qualifiedPrefix(qn)) {
             r.textEdit(replace(prefLoc, newName));
         }
diff --git a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Parameters.rsc b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Parameters.rsc
index 733c60aa8..3af12647d 100644
--- a/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Parameters.rsc
+++ b/rascal-lsp/src/main/rascal/lsp/lang/rascal/lsp/refactor/rename/Parameters.rsc
@@ -54,9 +54,10 @@ TModel augmentFormalUses(Tree tr, TModel tm, TModel(loc) getModel) {
         | loc f <- getModuleFile(tm) + (tm.paths<to>)
         , fileTm := getModel(f.top)
     };
+    rel[loc, loc] useDef = getUseDef(tm);
     visit (tr) {
         case (Expression) `<Expression e>(<{Expression ","}* _> <KeywordArguments[Expression] kwArgs>)`: {
-            funcKwDefs = keywordFormalDefs[tm.useDef[e.src]];
+            funcKwDefs = keywordFormalDefs[useDef[e.src]];
             // Only visit uses of our keyword arguments - do not go into nested calls
             top-down-break visit (kwArgs) {
                 case (KeywordArgument[Expression]) `<Name kw> = <Expression _>`: {