diff --git a/app/build.gradle b/app/build.gradle
index bbc936db2af49c316b8bc8b5c0897d3b09f3f850..885d14cbe773a57646051893bda7456d8905d01f 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -26,7 +26,6 @@ android {
         targetSdkVersion 33     // Android 13
 
         buildConfigField "String", "userAgent", "\"DAVx5\""
-        buildConfigField "String", "EMAIL_KEY", "\"${emailKey()}\""
 
         testInstrumentationRunner "at.bitfire.davdroid.CustomTestRunner"
 
@@ -78,12 +77,16 @@ android {
 
     buildTypes {
         debug {
+            buildConfigField "String", "EMAIL_KEY", "\"invalid\""
         }
+
         release {
             minifyEnabled true
             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules-release.pro'
 
             shrinkResources true
+
+            buildConfigField "String", "EMAIL_KEY", "\"${retrieveEmailKey()}\""
         }
     }
 
@@ -183,12 +186,14 @@ dependencies {
     testImplementation "com.squareup.okhttp3:mockwebserver:${versions.okhttp}"
 }
 
-def emailKey() {
+def retrieveEmailKey() {
     Properties properties = new Properties()
-    try {
-        properties.load(project.rootProject.file('local.properties').newDataInputStream())
-    } catch (ignored) {
-        // Ignore
+    properties.load(project.rootProject.file('local.properties').newDataInputStream())
+
+    String value = properties.getProperty("email.key")
+    if (value == null) {
+        throw new GradleException("email.key property not found in local.properties file")
     }
-    return properties.getProperty("email.key", "invalid")
+
+    return value
 }