diff --git a/packages/taler-harness/src/lint.ts b/packages/taler-harness/src/lint.ts
index 715227c7f..f13049710 100644
--- a/packages/taler-harness/src/lint.ts
+++ b/packages/taler-harness/src/lint.ts
@@ -136,13 +136,13 @@ function checkBasicConf(context: LintContext): BasicConf {
   const currencyEntry = cfg.getString("taler", "currency");
   let mainCurrency: string | undefined;
 
-  if (!currencyEntry.value) {
+  if (!currencyEntry.isDefined()) {
     context.numErr++;
     console.log("error: currency not defined in section TALER option CURRENCY");
     console.log("Aborting further checks.");
     process.exit(1);
   } else {
-    mainCurrency = currencyEntry.value.toUpperCase();
+    mainCurrency = currencyEntry.required().toUpperCase();
   }
 
   if (mainCurrency === "KUDOS") {
diff --git a/packages/taler-util/src/talerconfig.ts b/packages/taler-util/src/talerconfig.ts
index d86c58678..098f5f9a4 100644
--- a/packages/taler-util/src/talerconfig.ts
+++ b/packages/taler-util/src/talerconfig.ts
@@ -25,11 +25,14 @@
  */
 import { AmountJson } from "./amounts.js";
 import { Amounts } from "./amounts.js";
+import { Logger } from "./logging.js";
 
 import nodejs_path from "path";
 import nodejs_os from "os";
 import nodejs_fs from "fs";
 
+const logger = new Logger("talerconfig.ts");
+
 export class ConfigError extends Error {
   constructor(message: string) {
     super();
@@ -77,7 +80,7 @@ export class ConfigValue<T> {
   constructor(
     private sectionName: string,
     private optionName: string,
-    public value: string | undefined,
+    private value: string | undefined,
     private converter: (x: string) => T,
   ) {}
 
@@ -138,7 +141,7 @@ export function pathsub(
   lookup: (s: string, depth: number) => string | undefined,
   depth = 0,
 ): string {
-  if (depth >= 10) {
+  if (depth >= 128) {
     throw Error("recursion in path substitution");
   }
   let s = x;
@@ -624,15 +627,18 @@ export class Configuration {
   lookupVariable(x: string, depth: number = 0): string | undefined {
     // We loop up options in PATHS in upper case, as option names
     // are case insensitive
-    let val = this.findEntry("PATHS", x)?.value;
+    const val = this.findEntry("PATHS", x)?.value;
     if (val !== undefined) {
       return pathsub(val, (v, d) => this.lookupVariable(v, d), depth);
     }
+
     // Environment variables can be case sensitive, respect that.
     const envVal = process.env[x];
     if (envVal !== undefined) {
       return envVal;
     }
+
+    logger.warn(`unable to resolve variable '${x}'`);
     return;
   }
 
@@ -692,12 +698,28 @@ export class Configuration {
       "DOCDIR",
       `${installPrefix}/share/doc/taler/`,
     );
-    this.setStringSystemDefault("PATHS", "ICONDIR", `${installPrefix}/share/icons/`);
-    this.setStringSystemDefault("PATHS", "LOCALEDIR", `${installPrefix}/share/locale/`);
+    this.setStringSystemDefault(
+      "PATHS",
+      "ICONDIR",
+      `${installPrefix}/share/icons/`,
+    );
+    this.setStringSystemDefault(
+      "PATHS",
+      "LOCALEDIR",
+      `${installPrefix}/share/locale/`,
+    );
     this.setStringSystemDefault("PATHS", "PREFIX", `${installPrefix}/`);
     this.setStringSystemDefault("PATHS", "BINDIR", `${installPrefix}/bin`);
-    this.setStringSystemDefault("PATHS", "LIBDIR", `${installPrefix}/lib/taler/`);
-    this.setStringSystemDefault("PATHS", "DATADIR", `${installPrefix}/share/taler/`);
+    this.setStringSystemDefault(
+      "PATHS",
+      "LIBDIR",
+      `${installPrefix}/lib/taler/`,
+    );
+    this.setStringSystemDefault(
+      "PATHS",
+      "DATADIR",
+      `${installPrefix}/share/taler/`,
+    );
 
     this.loadDefaultsFromDir(baseConfigDir);
   }