diff --git a/mem0-ts/src/oss/src/vector_stores/redis.ts b/mem0-ts/src/oss/src/vector_stores/redis.ts
index c5d8394f7..8c274f7d5 100644
--- a/mem0-ts/src/oss/src/vector_stores/redis.ts
+++ b/mem0-ts/src/oss/src/vector_stores/redis.ts
@@ -133,6 +133,18 @@ function toSnakeCase(obj: Record<string, any>): Record<string, any> {
   );
 }
 
+// Build a RediSearch pre-filter expression from filters. Returns "*" (match
+// all) when there are no usable conditions — including an empty filters object
+// or one whose values are all null/undefined — since an empty expression is an
+// invalid RediSearch query (e.g. ` =>[KNN ...]`).
+export function buildRedisFilterExpr(filters?: SearchFilters): string {
+  if (!filters) return "*";
+  const conditions = Object.entries(toSnakeCase(filters))
+    .filter(([, value]) => value !== null && value !== undefined)
+    .map(([key, value]) => `@${key}:{${escapeRedisTagValue(value)}}`);
+  return conditions.length > 0 ? conditions.join(" ") : "*";
+}
+
 // Utility function to convert object keys to camelCase
 function toCamelCase(obj: Record<string, any>): Record<string, any> {
   if (typeof obj !== "object" || obj === null) return obj;
@@ -406,13 +418,7 @@ export class RedisDB implements VectorStore {
     filters?: SearchFilters,
   ): Promise<VectorStoreResult[]> {
     await this.initialize();
-    const snakeFilters = filters ? toSnakeCase(filters) : undefined;
-    const filterExpr = snakeFilters
-      ? Object.entries(snakeFilters)
-          .filter(([_, value]) => value !== null && value !== undefined)
-          .map(([key, value]) => `@${key}:{${escapeRedisTagValue(value)}}`)
-          .join(" ")
-      : "*";
+    const filterExpr = buildRedisFilterExpr(filters);
 
     const queryVector = new Float32Array(query).buffer;
 
@@ -655,13 +661,7 @@ export class RedisDB implements VectorStore {
     topK: number = 100,
   ): Promise<[VectorStoreResult[], number]> {
     await this.initialize();
-    const snakeFilters = filters ? toSnakeCase(filters) : undefined;
-    const filterExpr = snakeFilters
-      ? Object.entries(snakeFilters)
-          .filter(([_, value]) => value !== null && value !== undefined)
-          .map(([key, value]) => `@${key}:{${escapeRedisTagValue(value)}}`)
-          .join(" ")
-      : "*";
+    const filterExpr = buildRedisFilterExpr(filters);
 
     const searchOptions = {
       SORTBY: "created_at",
diff --git a/mem0-ts/src/oss/tests/redis.filter-expr.test.ts b/mem0-ts/src/oss/tests/redis.filter-expr.test.ts
new file mode 100644
index 000000000..43ed6c63b
--- /dev/null
+++ b/mem0-ts/src/oss/tests/redis.filter-expr.test.ts
@@ -0,0 +1,35 @@
+import { buildRedisFilterExpr } from "../src/vector_stores/redis";
+
+describe("buildRedisFilterExpr", () => {
+  it("returns '*' when filters is undefined", () => {
+    expect(buildRedisFilterExpr(undefined)).toBe("*");
+  });
+
+  it("returns '*' for an empty filters object", () => {
+    // Regression: previously produced "" -> invalid RediSearch query
+    // (` =>[KNN ...]`).
+    expect(buildRedisFilterExpr({})).toBe("*");
+  });
+
+  it("returns '*' when every filter value is null/undefined", () => {
+    expect(
+      buildRedisFilterExpr({ user_id: null as any, agent_id: undefined }),
+    ).toBe("*");
+  });
+
+  it("builds a tag clause for a single filter", () => {
+    expect(buildRedisFilterExpr({ user_id: "alice" })).toBe("@user_id:{alice}");
+  });
+
+  it("snake-cases keys and joins multiple clauses", () => {
+    expect(buildRedisFilterExpr({ userId: "alice", runId: "r1" })).toBe(
+      "@user_id:{alice} @run_id:{r1}",
+    );
+  });
+
+  it("drops null/undefined values but keeps the rest", () => {
+    expect(
+      buildRedisFilterExpr({ user_id: "alice", agent_id: null as any }),
+    ).toBe("@user_id:{alice}");
+  });
+});