diff --git a/lib/options-handler.ts b/lib/options-handler.ts
index 0210b380b1f..02f34f1863b 100755
--- a/lib/options-handler.ts
+++ b/lib/options-handler.ts
@@ -68,10 +68,10 @@ type OptionsType = {
     libs: Record<any, any>;
     remoteLibs: Record<any, any>;
     tools: Record<any, any>;
-    defaultLibs: string;
-    defaultCompiler: string;
-    compileOptions: string;
-    supportsBinary: boolean;
+    defaultLibs: Record<LanguageKey, string>;
+    defaultCompiler: Record<LanguageKey, string>;
+    compileOptions: Record<LanguageKey, string>;
+    supportsBinary: Record<LanguageKey, boolean>;
     supportsExecute: boolean;
     supportsLibraryCodeFilter: boolean;
     languages: Record<string, any>;
@@ -110,10 +110,10 @@ type OptionsType = {
 export class ClientOptionsHandler {
     compilerProps: CompilerProps['get'];
     ceProps: PropertyGetter;
-    supportsBinary: boolean;
-    supportsExecutePerLanguage: boolean;
+    supportsBinary: Record<LanguageKey, boolean>;
+    supportsExecutePerLanguage: Record<LanguageKey, boolean>;
     supportsExecute: boolean;
-    supportsLibraryCodeFilterPerLanguage: boolean;
+    supportsLibraryCodeFilterPerLanguage: Record<LanguageKey, boolean>;
     supportsLibraryCodeFilter: boolean;
     remoteLibs: Record<any, any>;
     options: OptionsType;
@@ -150,9 +150,8 @@ export class ClientOptionsHandler {
         this.supportsLibraryCodeFilterPerLanguage = this.compilerProps(languages, 'supportsLibraryCodeFilter', false);
         this.supportsLibraryCodeFilter = Object.values(this.supportsLibraryCodeFilterPerLanguage).some(value => value);
 
-        // TODO: Shouldn't have to cast here
-        const libs = this.parseLibraries(this.compilerProps(languages, 'libs') as any);
-        const tools = this.parseTools(this.compilerProps(languages, 'tools') as any);
+        const libs = this.parseLibraries(this.compilerProps<string>(languages, 'libs'));
+        const tools = this.parseTools(this.compilerProps<string>(languages, 'tools'));
 
         this.remoteLibs = {};
 
diff --git a/lib/properties.ts b/lib/properties.ts
index 6dbb8c29900..878d979e029 100644
--- a/lib/properties.ts
+++ b/lib/properties.ts
@@ -27,6 +27,8 @@ import path from 'path';
 
 import _ from 'underscore';
 
+import {LanguageKey} from '../types/languages.interfaces';
+
 import {logger} from './logger';
 import {PropertyGetter, PropertyValue, Widen} from './properties.interfaces';
 import {toProperty} from './utils';
@@ -175,37 +177,74 @@ export class CompilerProps {
      * @param {?function} fn - Transformation to give to each value found
      * @returns {*} Transformed value(s) found or fn(defaultValue)
      */
+
+    // A lot of overloads for a lot of different variants:
+    // const a = this.compilerProps(lang, property); // PropertyValue
+    // const b = this.compilerProps<number>(lang, property); // number
+    // const c = this.compilerProps(lang, property, 42); // number
+    // const d = this.compilerProps(lang, property, undefined, (x) => ["foobar"]); // string[]
+    // const e = this.compilerProps(lang, property, 42, (x) => ["foobar"]); // number | string[]
+    // if more than one language:
+    // const f = this.compilerProps(languages, property); // Record<LanguageKey, PropertyValue>
+    // const g = this.compilerProps<number>(languages, property); // Record<LanguageKey, number>
+    // const h = this.compilerProps(languages, property, 42); // Record<LanguageKey, number>
+    // const i = this.compilerProps(languages, property, undefined, (x) => ["foobar"]); // Record<LanguageKey, string[]>
+    // const j = this.compilerProps(languages, property, 42, (x) => ["foobar"]);//Record<LanguageKey, number | string[]>
+
+    // general overloads
+    get(base: string, property: string, defaultValue?: undefined, fn?: undefined): PropertyValue;
+    get<T extends PropertyValue>(
+        base: string,
+        property: string,
+        defaultValue: Widen<T>,
+        fn?: undefined,
+    ): typeof defaultValue;
+    get<T extends PropertyValue>(base: string, property: string, defaultValue?: PropertyValue, fn?: undefined): T;
+    // fn overloads
+    get<R>(
+        base: string,
+        property: string,
+        defaultValue?: undefined,
+        fn?: (item: PropertyValue, language?: any) => R,
+    ): R;
+    get<T extends PropertyValue, R>(
+        base: string,
+        property: string,
+        defaultValue: Widen<T>,
+        fn?: (item: typeof defaultValue, language?: any) => R,
+    ): R;
+    // container base general overloads
     get(
-        base: string | LanguageDef[] | Record<string, any>,
+        base: LanguageDef[] | Record<string, any>,
         property: string,
         defaultValue?: undefined,
         fn?: undefined,
-    ): PropertyValue;
+    ): Record<LanguageKey, PropertyValue>;
     get<T extends PropertyValue>(
-        base: string | LanguageDef[] | Record<string, any>,
+        base: LanguageDef[] | Record<string, any>,
         property: string,
         defaultValue: Widen<T>,
         fn?: undefined,
-    ): typeof defaultValue;
+    ): Record<LanguageKey, typeof defaultValue>;
     get<T extends PropertyValue>(
-        base: string | LanguageDef[] | Record<string, any>,
+        base: LanguageDef[] | Record<string, any>,
         property: string,
         defaultValue?: PropertyValue,
         fn?: undefined,
-    ): T;
-
+    ): Record<LanguageKey, T>;
+    // container base fn overloads
     get<R>(
-        base: string | LanguageDef[] | Record<string, any>,
+        base: LanguageDef[] | Record<string, any>,
         property: string,
         defaultValue?: undefined,
         fn?: (item: PropertyValue, language?: any) => R,
-    ): R;
+    ): Record<LanguageKey, R>;
     get<T extends PropertyValue, R>(
-        base: string | LanguageDef[] | Record<string, any>,
+        base: LanguageDef[] | Record<string, any>,
         property: string,
         defaultValue: Widen<T>,
-        fn?: (item: PropertyValue, language?: any) => R,
-    ): typeof defaultValue | R;
+        fn?: (item: typeof defaultValue, language?: any) => R,
+    ): Record<LanguageKey, R>;
 
     get(
         langs: string | LanguageDef[] | Record<string, any>,