diff --git a/bugsnag-android-core/src/main/java/com/bugsnag/android/Configuration.java b/bugsnag-android-core/src/main/java/com/bugsnag/android/Configuration.java
index f949147306..f7ba49134f 100644
--- a/bugsnag-android-core/src/main/java/com/bugsnag/android/Configuration.java
+++ b/bugsnag-android-core/src/main/java/com/bugsnag/android/Configuration.java
@@ -5,7 +5,6 @@
 import androidx.annotation.IntRange;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.annotation.VisibleForTesting;
 
 import java.io.File;
 import java.util.Map;
@@ -20,7 +19,6 @@ public class Configuration implements CallbackAware, MetadataAware, UserAware, F
 
     private static final int MIN_BREADCRUMBS = 0;
     private static final int MAX_BREADCRUMBS = 500;
-    private static final int VALID_API_KEY_LEN = 32;
     private static final long MIN_LAUNCH_CRASH_THRESHOLD_MS = 0;
 
     final ConfigInternal impl;
@@ -29,7 +27,6 @@ public class Configuration implements CallbackAware, MetadataAware, UserAware, F
      * Constructs a new Configuration object with default values.
      */
     public Configuration(@NonNull String apiKey) {
-        validateApiKey(apiKey);
         impl = new ConfigInternal(apiKey);
     }
 
@@ -47,32 +44,6 @@ static Configuration load(@NonNull Context context, @NonNull String apiKey) {
         return ConfigInternal.load(context, apiKey);
     }
 
-    private void validateApiKey(String value) {
-        if (isInvalidApiKey(value)) {
-            DebugLogger.INSTANCE.w("Invalid configuration. "
-                    + "apiKey should be a 32-character hexademical string, got " + value);
-        }
-    }
-
-    @VisibleForTesting
-    static boolean isInvalidApiKey(String apiKey) {
-        if (Intrinsics.isEmpty(apiKey)) {
-            throw new IllegalArgumentException("No Bugsnag API Key set");
-        }
-        if (apiKey.length() != VALID_API_KEY_LEN) {
-            return true;
-        }
-        // check whether each character is hexadecimal (either a digit or a-f).
-        // this avoids using a regex to improve startup performance.
-        for (int k = 0; k < VALID_API_KEY_LEN; k++) {
-            char chr = apiKey.charAt(k);
-            if (!Character.isDigit(chr) && (chr < 'a' || chr > 'f')) {
-                return true;
-            }
-        }
-        return false;
-    }
-
     private void logNull(String property) {
         getLogger().e("Invalid null value supplied to config." + property + ", ignoring");
     }
@@ -89,7 +60,6 @@ public String getApiKey() {
      * Changes the API key used for events sent to Bugsnag.
      */
     public void setApiKey(@NonNull String apiKey) {
-        validateApiKey(apiKey);
         impl.setApiKey(apiKey);
     }
 
diff --git a/bugsnag-android-core/src/main/java/com/bugsnag/android/internal/ImmutableConfig.kt b/bugsnag-android-core/src/main/java/com/bugsnag/android/internal/ImmutableConfig.kt
index 8ff97eab96..13df89911f 100644
--- a/bugsnag-android-core/src/main/java/com/bugsnag/android/internal/ImmutableConfig.kt
+++ b/bugsnag-android-core/src/main/java/com/bugsnag/android/internal/ImmutableConfig.kt
@@ -9,6 +9,7 @@ import com.bugsnag.android.BreadcrumbType
 import com.bugsnag.android.Configuration
 import com.bugsnag.android.Connectivity
 import com.bugsnag.android.DebugLogger
+import com.bugsnag.android.DebugLogger.w
 import com.bugsnag.android.DefaultDelivery
 import com.bugsnag.android.Delivery
 import com.bugsnag.android.DeliveryParams
@@ -176,6 +177,34 @@ internal fun convertToImmutableConfig(
     )
 }
 
+private fun validateApiKey(value: String) {
+    if (isInvalidApiKey(value)) {
+        w(
+            "Invalid configuration. "
+                    + "apiKey should be a 32-character hexademical string, got " + value
+        )
+    }
+}
+
+@VisibleForTesting
+fun isInvalidApiKey(apiKey: String): Boolean {
+    if (apiKey.isNullOrEmpty()) {
+        throw IllegalArgumentException("No Bugsnag API Key set")
+    }
+    if (apiKey.length != VALID_API_KEY_LEN) {
+        return true
+    }
+    // check whether each character is hexadecimal (either a digit or a-f).
+    // this avoids using a regex to improve startup performance.
+    for (k in 0 until VALID_API_KEY_LEN) {
+        val chr = apiKey[k]
+        if (!Character.isDigit(chr) && (chr < 'a' || chr > 'f')) {
+            return true
+        }
+    }
+    return false
+}
+
 internal fun sanitiseConfiguration(
     appContext: Context,
     configuration: Configuration,
@@ -188,6 +217,8 @@ internal fun sanitiseConfiguration(
         packageManager.getApplicationInfo(packageName, PackageManager.GET_META_DATA)
     }.getOrNull()
 
+    validateApiKey(configuration.apiKey)
+
     // populate releaseStage
     if (configuration.releaseStage == null) {
         configuration.releaseStage = when {
@@ -251,3 +282,4 @@ private fun populateBuildUuid(appInfo: ApplicationInfo?): String? {
 
 internal const val RELEASE_STAGE_DEVELOPMENT = "development"
 internal const val RELEASE_STAGE_PRODUCTION = "production"
+internal const val VALID_API_KEY_LEN = 32
\ No newline at end of file
diff --git a/bugsnag-android-core/src/test/java/com/bugsnag/android/ApiKeyValidationTest.kt b/bugsnag-android-core/src/test/java/com/bugsnag/android/ApiKeyValidationTest.kt
index 3e7e52214d..d146ba3e26 100644
--- a/bugsnag-android-core/src/test/java/com/bugsnag/android/ApiKeyValidationTest.kt
+++ b/bugsnag-android-core/src/test/java/com/bugsnag/android/ApiKeyValidationTest.kt
@@ -1,37 +1,33 @@
 package com.bugsnag.android
 
+import com.bugsnag.android.internal.isInvalidApiKey
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertTrue
 import org.junit.Test
 
-class ApiKeyValidationTest {
-
-    @Test(expected = IllegalArgumentException::class)
-    fun testNullApiKey() {
-        Configuration.isInvalidApiKey(null)
-    }
+internal class ApiKeyValidationTest {
 
     @Test(expected = IllegalArgumentException::class)
     fun testEmptyApiKey() {
-        Configuration.isInvalidApiKey("")
+        isInvalidApiKey("")
     }
 
     @Test
     fun testWrongSizeApiKey() {
-        assertTrue(Configuration.isInvalidApiKey("abfe05f"))
-        assertTrue(Configuration.isInvalidApiKey("5d1ec5bd39a74caa1267142706a7fb212"))
+        assertTrue(isInvalidApiKey("abfe05f"))
+        assertTrue(isInvalidApiKey("5d1ec5bd39a74caa1267142706a7fb212"))
     }
 
     @Test
     fun testSettingNonHexApiKey() {
-        assertTrue(Configuration.isInvalidApiKey("5d1ec5bd3Ga74caa1267142706a7fb21"))
-        assertTrue(Configuration.isInvalidApiKey("5d1ec5bd39a7%caa1267_42706P7fb212"))
-        assertFalse(Configuration.isInvalidApiKey("5d1ec5bd39a74caa1267142706a7fb21"))
+        assertTrue(isInvalidApiKey("5d1ec5bd3Ga74caa1267142706a7fb21"))
+        assertTrue(isInvalidApiKey("5d1ec5bd39a7%caa1267_42706P7fb212"))
+        assertFalse(isInvalidApiKey("5d1ec5bd39a74caa1267142706a7fb21"))
     }
 
     @Test
     fun setApiKey() {
-        assertFalse(Configuration.isInvalidApiKey("5d1ec5bd39a74caa1267142706a7fb21"))
-        assertFalse(Configuration.isInvalidApiKey("000005bd39a74caa1267142706a7fb21"))
+        assertFalse(isInvalidApiKey("5d1ec5bd39a74caa1267142706a7fb21"))
+        assertFalse(isInvalidApiKey("000005bd39a74caa1267142706a7fb21"))
     }
 }