diff --git a/packages/config-loader/src/sources/EnvConfigSource.ts b/packages/config-loader/src/sources/EnvConfigSource.ts
index ffb615754f..988110b370 100644
--- a/packages/config-loader/src/sources/EnvConfigSource.ts
+++ b/packages/config-loader/src/sources/EnvConfigSource.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { AppConfig, CONFIG_KEY_PART_PATTERN } from '@backstage/config';
+import { AppConfig } from '@backstage/config';
 import { assertError } from '@backstage/errors';
 import { JsonObject } from '@backstage/types';
 import { AsyncConfigSourceGenerator, ConfigSource } from './types';
@@ -84,6 +84,9 @@ export class EnvConfigSource implements ConfigSource {
 
 const ENV_PREFIX = 'APP_CONFIG_';
 
+// Update the same pattern in config package if this is changed
+const CONFIG_KEY_PART_PATTERN = /^[a-z][a-z0-9]*(?:[-_:][a-z0-9]+)*$/i;
+
 /**
  * Read runtime configuration from the environment.
  *
diff --git a/packages/config/report.api.md b/packages/config/report.api.md
index 2963960973..94c4652b44 100644
--- a/packages/config/report.api.md
+++ b/packages/config/report.api.md
@@ -43,9 +43,6 @@ export type Config = {
   getOptionalStringArray(key: string): string[] | undefined;
 };
 
-// @public
-export const CONFIG_KEY_PART_PATTERN: RegExp;
-
 // @public
 export class ConfigReader implements Config {
   constructor(
diff --git a/packages/config/src/constants.ts b/packages/config/src/constants.ts
deleted file mode 100644
index 35a1d3652b..0000000000
--- a/packages/config/src/constants.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Copyright 2025 The Backstage Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * The pattern that config keys must match.
- *
- * @remarks
- * keys must only contain the letters `a` through `z` and digits, in groups separated by
- * dashes or underscores and colon. Additionally, the very first character of each such group
- * must be a letter, not a digit
- *
- * @public
- */
-export const CONFIG_KEY_PART_PATTERN = /^[a-z][a-z0-9]*(?:[-_:][a-z0-9]+)*$/i;
diff --git a/packages/config/src/index.ts b/packages/config/src/index.ts
index 2f3ade0189..c6254e97ba 100644
--- a/packages/config/src/index.ts
+++ b/packages/config/src/index.ts
@@ -29,4 +29,3 @@ export type {
 export { readDurationFromConfig } from './readDurationFromConfig';
 export { ConfigReader } from './reader';
 export type { AppConfig, Config } from './types';
-export { CONFIG_KEY_PART_PATTERN } from './constants';
diff --git a/packages/config/src/reader.ts b/packages/config/src/reader.ts
index 18f010daac..8186ee8faa 100644
--- a/packages/config/src/reader.ts
+++ b/packages/config/src/reader.ts
@@ -17,7 +17,8 @@
 import { JsonObject, JsonValue } from '@backstage/types';
 import { AppConfig, Config } from './types';
 
-import { CONFIG_KEY_PART_PATTERN } from './constants';
+// Update the same pattern in config-loader package if this is changed
+const CONFIG_KEY_PART_PATTERN = /^[a-z][a-z0-9]*(?:[-_:][a-z0-9]+)*$/i;
 
 function isObject(value: JsonValue | undefined): value is JsonObject {
   return typeof value === 'object' && value !== null && !Array.isArray(value);