diff --git a/packages/typescript-client/src/column-mapper.ts b/packages/typescript-client/src/column-mapper.ts
index c1a6d3d654..a9303f553e 100644
--- a/packages/typescript-client/src/column-mapper.ts
+++ b/packages/typescript-client/src/column-mapper.ts
@@ -193,6 +193,13 @@ export function encodeWhereClause(
 ): string {
   if (!whereClause || !encode) return whereClause ?? ``
 
+  // Handle double-quoted identifiers: "userId" -> "user_id"
+  // These come from query builders like @tanstack/electric-db-collection
+  // and need encoding just like unquoted identifiers
+  whereClause = whereClause.replace(/"([^"]+)"/g, (_, identifier) => {
+    return `"${encode(identifier)}"`
+  })
+
   // SQL keywords that should not be transformed (common ones)
   const sqlKeywords = new Set([
     `SELECT`,
diff --git a/packages/typescript-client/test/column-mapper.test.ts b/packages/typescript-client/test/column-mapper.test.ts
index dfd18c8091..7017802c49 100644
--- a/packages/typescript-client/test/column-mapper.test.ts
+++ b/packages/typescript-client/test/column-mapper.test.ts
@@ -363,12 +363,13 @@ describe(`encodeWhereClause`, () => {
     ).toBe(`first_name = 'John' AND last_name = 'Doe' AND user_id = $1`)
   })
 
-  it(`should not transform double-quoted identifiers`, () => {
-    // Postgres uses double quotes for case-sensitive identifiers
-    expect(encodeWhereClause(`"userId" = $1`, encode)).toBe(`"userId" = $1`)
+  it(`should transform double-quoted identifiers`, () => {
+    // Query builders like @tanstack/electric-db-collection use double quotes
+    // for identifiers, and these need encoding just like unquoted identifiers
+    expect(encodeWhereClause(`"userId" = $1`, encode)).toBe(`"user_id" = $1`)
 
     expect(encodeWhereClause(`"User"."createdAt" = $1`, encode)).toBe(
-      `"User"."createdAt" = $1`
+      `"user"."created_at" = $1`
     )
   })
 
@@ -382,7 +383,7 @@ describe(`encodeWhereClause`, () => {
   it(`should handle mixed quoted and unquoted identifiers`, () => {
     expect(
       encodeWhereClause(`userId = $1 AND "CaseSensitive" = $2`, encode)
-    ).toBe(`user_id = $1 AND "CaseSensitive" = $2`)
+    ).toBe(`user_id = $1 AND "case_sensitive" = $2`)
   })
 })