diff --git a/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/param/CreateInvoiceParam.java b/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/param/CreateInvoiceParam.java
index f472a77..23e1587 100644
--- a/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/param/CreateInvoiceParam.java
+++ b/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/param/CreateInvoiceParam.java
@@ -21,12 +21,16 @@ public class CreateInvoiceParam implements Request.Param {
     public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("description=").append(encode(description))
-                .append("&amountSat=").append(encode(String.valueOf(amountSat)))
                 .append("&amountSat=").append(amountSat == null ? "" : amountSat)
                 .append("&expirySeconds=").append(expirySeconds == null ? "" : expirySeconds)
                 .append("&externalId=").append(encode(externalId));
         if (webhookUrl != null) {
-            sb.append("&webhookUrl=").append(encode(webhookUrl.toString()));
+            String urlString = webhookUrl.toString();
+            if (urlString.contains("?")) {
+                sb.append("&webhookUrl=").append(encode(urlString));
+            } else {
+                sb.append("&webhookUrl=").append(urlString);
+            }
         }
         return sb.toString();
     }
diff --git a/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayBolt11InvoiceInvoiceResponse.java b/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayBolt11InvoiceInvoiceResponse.java
index 7dbd4c5..f8fedbb 100644
--- a/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayBolt11InvoiceInvoiceResponse.java
+++ b/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayBolt11InvoiceInvoiceResponse.java
@@ -3,9 +3,11 @@
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 import lombok.NoArgsConstructor;
+import lombok.ToString;
 
 @EqualsAndHashCode(callSuper = true)
 @Data
 @NoArgsConstructor
+@ToString(callSuper = true)
 public class PayBolt11InvoiceInvoiceResponse extends PayInvoiceResponse {
 }
diff --git a/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayLightningAddressInvoiceResponse.java b/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayLightningAddressInvoiceResponse.java
index e59583e..a7dd136 100644
--- a/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayLightningAddressInvoiceResponse.java
+++ b/phoenixd-model/src/main/java/xyz/tcheeric/phoenixd/model/response/PayLightningAddressInvoiceResponse.java
@@ -3,9 +3,11 @@
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 import lombok.NoArgsConstructor;
+import lombok.ToString;
 
 @EqualsAndHashCode(callSuper = true)
 @Data
 @NoArgsConstructor
+@ToString(callSuper = true)
 public class PayLightningAddressInvoiceResponse extends PayInvoiceResponse {
 }
diff --git a/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java b/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java
index 73bad47..ca8cbbd 100644
--- a/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java
+++ b/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java
@@ -175,10 +175,14 @@ public String replacePathVariables(String path, Request.Param param) {
         Field[] fields = param.getClass().getDeclaredFields();
         for (Field field : fields) {
             field.setAccessible(true);
-            Object value = field.get(param);
-            if (value != null) {
-                String placeholder = "{" + field.getName() + "}";
-                path = path.replace(placeholder, value.toString());
+            try {
+                Object value = field.get(param);
+                if (value != null) {
+                    String placeholder = "{" + field.getName() + "}";
+                    path = path.replace(placeholder, value.toString());
+                }
+            } catch (IllegalAccessException e) {
+                throw new RuntimeException(e);
             }
         }
         return path;
diff --git a/phoenixd-test/src/test/java/xyz/tcheeric/phoenixd/test/TestUtils.java b/phoenixd-test/src/test/java/xyz/tcheeric/phoenixd/test/TestUtils.java
index d1cb281..e250a35 100644
--- a/phoenixd-test/src/test/java/xyz/tcheeric/phoenixd/test/TestUtils.java
+++ b/phoenixd-test/src/test/java/xyz/tcheeric/phoenixd/test/TestUtils.java
@@ -6,12 +6,8 @@
 import java.util.Properties;
 
 public final class TestUtils {
-    private TestUtils() {
-    }
-
-    public static void setBaseUrl(String baseUrl) {
-        try {
     private static final String CONFIG_FIELD_NAME = "CONFIG";
+    private static final String PHOENIXD_BASE_URL_KEY = "phoenixd.base_url";
 
     private TestUtils() {
     }