diff --git a/README.md b/README.md
index 085d977..0c9c7a5 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,7 @@ To start the emulator and begin debugging automatically:
   "args": ["--dap"],
   "stopOnEntry": true,
   "cwd": "${workspaceFolder}",
+  "srcDirs": ["${workspaceFolder}/lib/src", ...],
   "trace": true
 }
 ```
@@ -75,6 +76,7 @@ To start the emulator and begin debugging automatically:
 * `args`: Enter whatever arguments your emulator needs to enable DAP server.
 * `stopOnEntry`: Set to `true` to halt at program start.
 * `cwd`: Working directory.
+* `srcDirs`: Optional additional list of paths to lookup for source files
 * `trace`: Enables DAP message logging for troubleshooting.
 
 ### Attach to a Running Emulator
@@ -142,6 +144,7 @@ for the pack is being received.
 List of emulators supporting this variation of DAP:
 
 * Emu <img src="https://raw.githubusercontent.com/X65/emu/main/emu.gif" alt="Emu"> — The [X65 Computer](https://x65.zone/) Emulator.
+* Steckschwein <img src="https://www.steckschwein.de/steckschwein32.png" alt="Steckschwein Emulator"> — The [Steckschwein](https://www.steckschwein.de/) Emulator.
 
 If you know any other, please [create a PR][4] with an update to the list.
 
diff --git a/package.json b/package.json
index 05db837..2c9ac85 100644
--- a/package.json
+++ b/package.json
@@ -178,6 +178,14 @@
 								"type": "string",
 								"description": "Absolute path to the working directory.",
 								"default": "${cwd}"
+							},
+							"srcDirs": {
+								"type": "array",
+								"items": {
+									"type": "string"
+								},
+								"description": "An additional list of lookup paths for source files - e.g. required if we step from main debug code into a subroutine of a library",
+								"default": false
 							}
 						}
 					},
@@ -203,6 +211,14 @@
 								"type": "boolean",
 								"description": "Run without debugging.",
 								"default": false
+							},
+							"srcDirs": {
+								"type": "array",
+								"items": {
+									"type": "string"
+								},
+								"description": "An additional list of lookup paths for source files - e.g. required if we step from main debug code into a subroutine of a library",
+								"default": false
 							}
 						}
 					}
diff --git a/src/cc65Debug.ts b/src/cc65Debug.ts
index 4590ded..7c8ad8a 100644
--- a/src/cc65Debug.ts
+++ b/src/cc65Debug.ts
@@ -12,6 +12,7 @@
  */
 
 import { type ChildProcessWithoutNullStreams, spawn } from "node:child_process";
+import * as fs from "node:fs";
 import * as path from "node:path";
 import { Logger, LoggingDebugSession, TerminatedEvent, logger } from "@vscode/debugadapter";
 import type { DebugProtocol } from "@vscode/debugprotocol";
@@ -52,6 +53,8 @@ interface IRequestArguments extends DebugProtocol.LaunchRequestArguments {
 	trace?: boolean;
 	/** run without debugging */
 	noDebug?: boolean;
+	/** An additional list of lookup paths for source files - e.g. required if we step from main debug code into a subroutine of a library */
+	srcDirs?: string[];
 }
 
 interface ILaunchRequestArguments extends IRequestArguments {
@@ -105,6 +108,11 @@ export class Cc65DebugSession extends LoggingDebugSession {
 		this.setDebuggerLinesStartAt1(true);
 		this.setDebuggerColumnsStartAt1(true);
 
+		const srcDirs: string[] = this._session.configuration.srcDirs || [];
+
+		this._debugPathBases = [
+			...new Set([...this._debugPathBases, ...((srcDirs as string[]) ?? [])]),
+		];
 		// make sure to 'Stop' the buffered logging if 'trace' is not set
 		logger.setup(
 			this._session.configuration.trace ? Logger.LogLevel.Verbose : Logger.LogLevel.Stop,
@@ -696,10 +704,14 @@ export class Cc65DebugSession extends LoggingDebugSession {
 				showUser: true,
 			});
 		}
-
+		const dbgFileBaseName = path.basename(sourceBase);
+		const dbgFileSize = fs.statSync(source.path).size;
 		const dbgFile = this._debugData?.file.find((file) => {
 			const filePath = `${path.posix.sep}${normalizePath(file.name)}`;
-			return filePath.endsWith(`${path.posix.sep}${sourceBase}`);
+			return (
+				dbgFileSize === file.size &&
+				filePath.endsWith(`${path.posix.sep}${dbgFileBaseName}`)
+			);
 		});
 
 		if (!response.body) response.body = { breakpoints: [] };
@@ -717,7 +729,7 @@ export class Cc65DebugSession extends LoggingDebugSession {
 		}
 
 		// Store path base for later name reconstruction
-		const fileBase = normalizePath(dbgFile.name).slice(0, -sourceBase.length);
+		const fileBase = sourceBase.slice(0, -normalizePath(dbgFile.name).length);
 		if (!this._debugPathBases.includes(fileBase)) this._debugPathBases.push(fileBase);
 
 		// map source lines to memory addresses
@@ -926,9 +938,15 @@ export class Cc65DebugSession extends LoggingDebugSession {
 	// --------------------------------------------------------------------
 	private dbgFile2workspace(dbgFile: DbgFile) {
 		const fileName = normalizePath(dbgFile.name);
-		for (const base of this._debugPathBases) {
-			if (fileName.startsWith(base)) {
-				return fileName.slice(base.length);
+		// lookup relative to workspaceFolder
+		const workspaceFolder = normalizePath(
+			path.resolve(this._session.workspaceFolder?.uri.fsPath || "."),
+		);
+		// build path and do fs lookup
+		for (const pathBase of this._debugPathBases) {
+			const candidate = path.resolve(workspaceFolder, pathBase, fileName);
+			if (fs.existsSync(candidate) && fs.statSync(candidate).size === dbgFile.size) {
+				return normalizePath(path.relative(workspaceFolder, candidate));
 			}
 		}
 	}