diff --git a/src/filter.ts b/src/filter.ts
index 95a0498..66504be 100644
--- a/src/filter.ts
+++ b/src/filter.ts
@@ -3,17 +3,17 @@ import { getRegexFromString, getValueFromObject, isNumber, log, toNumber } from
 /**
  * Functions to check if filter condition is met
  */
-const operatorHandlers: { [key in FilterOperator]: (val: string | number | undefined, expectedVal: string | number | undefined) => boolean } = {
+const operatorHandlers: { [key in FilterOperator]: (val: FilterValueType, expectedVal: FilterValueType) => boolean } = {
     "exists": val => val !== undefined,
     "not_exists": val => val === undefined,
-    "contains": (val, searchString) => val !== undefined && val.toString().indexOf(searchString!.toString()) != -1,
+    "contains": (val, searchString) => val !== undefined && val !== null && val.toString().indexOf(searchString!.toString()) != -1,
     "=": (val, expectedVal) => isNumber(val) || isNumber(expectedVal) ? toNumber(val) == toNumber(expectedVal) : val == expectedVal,
     ">": (val, expectedVal) => toNumber(val) > toNumber(expectedVal),
     "<": (val, expectedVal) => toNumber(val) < toNumber(expectedVal),
     ">=": (val, expectedVal) => toNumber(val) >= toNumber(expectedVal),
     "<=": (val, expectedVal) => toNumber(val) <= toNumber(expectedVal),
     "matches": (val, pattern) => {
-        if (val === undefined) {
+        if (val === undefined || val === null) {
             return false;
         }
 
@@ -62,7 +62,7 @@ export class Filter {
      * @param entityData Hass entity data
      * @param state State override - battery state/level
      */
-    private getValue(entityData: any, state?: string): string | undefined {
+    private getValue(entityData: any, state?: string): FilterValueType {
         if (!this.config.name) {
             log("Missing filter 'name' property");
             return;
@@ -79,13 +79,16 @@ export class Filter {
      * Checks whether value meets the filter conditions.
      * @param val Value to validate
      */
-    private meetsExpectations(val: string | number | undefined): boolean {
+    private meetsExpectations(val: FilterValueType): boolean {
 
         let operator = this.config.operator;
         if (!operator) {
             if (this.config.value === undefined) {
                 operator = "exists";
             }
+            else if (this.config.value === null) {
+                operator = "=";
+            }
             else {
                 const expectedVal = this.config.value.toString();
                 const regex = getRegexFromString(expectedVal);
diff --git a/src/typings.d.ts b/src/typings.d.ts
index c88aac5..cc204de 100644
--- a/src/typings.d.ts
+++ b/src/typings.d.ts
@@ -153,6 +153,11 @@ type FilterGroups = "exclude" | "include";
  */
 type FilterOperator = "exists" | "not_exists" | "=" | ">" | "<" | ">=" | "<=" | "contains" | "matches";
 
+/**
+ * Allowed filter value types
+ */
+type FilterValueType  = string | number | boolean | null | undefined;
+
 /**
  * Filter object
  */
@@ -170,7 +175,7 @@ interface IFilter {
     /**
      * Value to compare with the extracted one
      */
-    value?: string | number;
+    value?: FilterValueType;
 }
 
 interface IBatteryEntityConfig {
diff --git a/src/utils.ts b/src/utils.ts
index 644cf71..9494e99 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -17,8 +17,8 @@ export const log = (message: string, level: "warn" | "error" = "warn") => {
  * Checks whether given value is a number
  * @param val String value to check
  */
-export const isNumber = (value: string | number | undefined): boolean => {
-    if (value === undefined) {
+export const isNumber = (value: string | number | boolean | null | undefined): boolean => {
+    if (value === undefined || value === null || typeof value === "boolean") {
         return false;
     }
 
@@ -27,7 +27,7 @@ export const isNumber = (value: string | number | undefined): boolean => {
         value = value.replace(",", ".");
     }
 
-    return (value!== undefined && value !== null && value !== '' && !isNaN(Number(value)))
+    return value !== '' && !isNaN(Number(value));
 }
 
 /**
@@ -35,7 +35,7 @@ export const isNumber = (value: string | number | undefined): boolean => {
  * @param value String value to convert
  * @returns Result number
  */
-export const toNumber = (value: string | number | undefined): number => {
+export const toNumber = (value: string | number | boolean | null | undefined): number => {
     if (typeof(value) == "string") {
         // trying to solve decimal number formatting in some langs
         value = value.replace(",", ".");
@@ -153,7 +153,7 @@ export const getRegexFromString = (ruleVal: string): RegExp | null => {
  * @param path Path to the value
  * @returns Value from the path
  */
-export const getValueFromObject = (dataObject: any, path: string): string | undefined => {
+export const getValueFromObject = (dataObject: any, path: string): string | number | boolean | null | undefined => {
     const chunks = path.split(".");
 
     for (let i = 0; i < chunks.length; i++) {
@@ -167,5 +167,5 @@ export const getValueFromObject = (dataObject: any, path: string): string | unde
         dataObject = JSON.stringify(dataObject);
     }
 
-    return dataObject === undefined ? undefined : dataObject.toString();
+    return dataObject;
 }
\ No newline at end of file
diff --git a/test/other/filter.test.ts b/test/other/filter.test.ts
index d45c8b6..ba111fe 100644
--- a/test/other/filter.test.ts
+++ b/test/other/filter.test.ts
@@ -118,6 +118,25 @@ describe("Filter", () => {
 
         expect(isValid).toBe(expectedIsVlid);
     })
+    test.each([
+        [44, <FilterOperator>"<", "44,1", true],
+        [44, <FilterOperator>">", "44.1", false],
+        [true, <FilterOperator>"=", "false", false],
+        [true, <FilterOperator>"=", "true", false],
+        [true, <FilterOperator>"=", true, true],
+        [true, undefined, true, true],
+        [false, undefined, true, false],
+        [true, undefined, false, false],
+    ])("non mixed types of values", (attributeValue: FilterValueType, operator: FilterOperator | undefined, value: FilterValueType, expectedIsVlid: boolean) => {
+        const hassMock = new HomeAssistantMock();
+
+        const entity = hassMock.addEntity("Entity name", "ok", { entity_attrib: attributeValue });
+
+        const filter = new Filter({ name: "attributes.entity_attrib", operator, value });
+        const isValid = filter.isValid(entity);
+
+        expect(isValid).toBe(expectedIsVlid);
+    })
 
     test.each([
         [{ state: "45", device: { name: "Device name" } }, "path.missing", "Device name", false],