diff --git a/package.json b/package.json
index e458b78e8..cef895056 100644
--- a/package.json
+++ b/package.json
@@ -100,7 +100,7 @@
     "semver": "^7.1.3",
     "tslint": "^6.1.0",
     "tslint-config-standard": "^9.0.0",
-    "typescript": "3.8.3",
+    "typescript": "3.9.7",
     "typescript-json-schema": "^0.42.0",
     "util.promisify": "^1.0.1"
   },
@@ -112,6 +112,7 @@
     "diff": "^4.0.1",
     "make-error": "^1.1.1",
     "source-map-support": "^0.5.17",
+    "tsconfig-paths": "^3.9.0",
     "yn": "3.1.1"
   }
 }
diff --git a/src/index.ts b/src/index.ts
index 2b7513f2d..eef665f78 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -4,6 +4,7 @@ import * as ynModule from 'yn'
 import { BaseError } from 'make-error'
 import * as util from 'util'
 import * as _ts from 'typescript'
+import { debugIt } from './resolver'
 
 /**
  * Does this version of node obey the package.json "type" field
@@ -382,6 +383,9 @@ export function register (opts: RegisterOptions = {}): Register {
   // Register the extensions.
   registerExtensions(service.options.preferTsExts, extensions, service, originalJsHandler)
 
+  console.dir(service.config, {depth: 10})
+  debugIt(service.config)
+
   return service
 }
 
diff --git a/src/resolver.ts b/src/resolver.ts
new file mode 100644
index 000000000..e69e34c1c
--- /dev/null
+++ b/src/resolver.ts
@@ -0,0 +1,98 @@
+import type * as _ts from 'typescript';
+import {getAbsoluteMappingEntries, MappingEntry} from 'tsconfig-paths/lib/mapping-entry';
+import {builtinModules as builtinModulesArray} from 'module';
+
+const builtinModules = new Set(builtinModulesArray);
+
+export function debugIt(config: _ts.ParsedCommandLine) {
+  if(config.options.baseUrl != null) {
+    const mappingEntries = getAbsoluteMappingEntries(config.options.baseUrl!, config.options.paths ?? {}, true);
+    console.dir(mappingEntries);
+    console.dir(getPathsToTry(mappingEntries, 'okeydokey'));
+  }
+}
+
+export function getPathsToTry(
+  absolutePathMappings: ReadonlyArray<MappingEntry>,
+  requestedModule: string
+): ReadonlyArray<string> | undefined {
+  if (
+    !absolutePathMappings ||
+    !requestedModule ||
+    requestedModule[0] === "."
+  ) {
+    return undefined;
+  }
+
+  const candidates: Array<string> = [];
+  for (const entry of absolutePathMappings) {
+    const starMatch =
+      entry.pattern === requestedModule
+        ? ""
+        : matchStar(entry.pattern, requestedModule);
+    if (starMatch !== undefined) {
+      for (const physicalPathPattern of entry.paths) {
+        const physicalPath = physicalPathPattern.replace("*", starMatch);
+        candidates.push(physicalPath);
+      }
+    }
+  }
+  return candidates;
+}
+
+/**
+ * Matches pattern with a single star against search.
+ * Star must match at least one character to be considered a match.
+ * @param pattern for example "foo*"
+ * @param search for example "fooawesomebar"
+ * @returns the part of search that * matches, or undefined if no match.
+ */
+function matchStar(pattern: string, search: string): string | undefined {
+  if (search.length < pattern.length) {
+    return undefined;
+  }
+  if (pattern === "*") {
+    return search;
+  }
+  const star = pattern.indexOf("*");
+  if (star === -1) {
+    return undefined;
+  }
+  const part1 = pattern.substring(0, star);
+  const part2 = pattern.substring(star + 1);
+  if (search.substr(0, star) !== part1) {
+    return undefined;
+  }
+  if (search.substr(search.length - part2.length) !== part2) {
+    return undefined;
+  }
+  return search.substr(star, search.length - part2.length);
+}
+
+// function createMappings(config: _ts.ParsedCommandLine): ResolverCandidates {
+//   const ret: ResolverCandidates = {};
+
+//   if(config.options.baseUrl != null) {
+//     ret.pathsAbs = Object.create(null);
+//     ret.baseUrlAbs = config.options.baseUrl;
+//     if(config.options.paths) {
+//       for(const [pattern, candidates] of Object.entries(config.options.paths)) {
+//         ret.pathsAbs![pattern] = candidates.map(candidate => joinPath(config.options.baseUrl!, candidate));
+//       }
+//     }
+//   }
+
+//   config.options.rootDirs = config.options.rootDirs?.slice();
+
+//   return ret;
+// }
+
+// function joinPath(a: string, b: string) {
+//   return require('path').join(a, b).replace('\\', '/');
+// }
+
+// interface ResolverCandidates {
+//   baseUrlAbs?: string;
+//   rootDirsAbs?: string[];
+//   pathsAbs?: Record<string, Array<string>>;
+// }
diff --git a/tsconfig.json b/tsconfig.json
index 465293630..3636e90cc 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -12,7 +12,17 @@
     "sourceMap": true,
     "inlineSources": true,
     "types": ["node", "mocha"],
-    "stripInternal": true
+    "stripInternal": true,
+    "baseUrl": "src",
+    "paths": {
+      // "*": ["generated/*", "bundled/*"],
+      "/what-*": ["generated/*", "bundled/*"],
+      "/*-what": ["generated/*", "bundled/*"]
+    },
+    "rootDirs": [
+      "src",
+      "generated/src"
+    ]
   },
   "include": [
     "src/**/*"