diff --git a/core/AmUtils.cpp b/core/AmUtils.cpp
index e78ed9e7..e06fe4ce 100644
--- a/core/AmUtils.cpp
+++ b/core/AmUtils.cpp
@@ -96,6 +96,7 @@ string uint128ToStr(__uint128_t val) { return num2str<__uint128_t>(val); }
 string int2str(unsigned long long val) { return num2str<unsigned long long>(val); }
 string int2str(unsigned int val) { return num2str<unsigned int>(val); }
 string int2str(int val) { return num2str<int>(val); }
+string int2str(unsigned long int val) { return num2str<unsigned long int>(val); }
 string long2str(long int val) { return num2str<long int>(val); }
 string longlong2str(long long int val) { return num2str<long long int>(val); }
 
diff --git a/core/AmUtils.h b/core/AmUtils.h
index 50ca486c..93b77929 100644
--- a/core/AmUtils.h
+++ b/core/AmUtils.h
@@ -79,6 +79,11 @@ string int2str(unsigned int val);
  */
 string long2str(long int val);
 
+/**
+ * Convert an unsigned long to a string.
+ */
+string int2str(unsigned long int val);
+
 /**
  * Convert a long long to a string.
  */
diff --git a/core/sip/trans_layer.cpp b/core/sip/trans_layer.cpp
index c3dde022..50077bdc 100644
--- a/core/sip/trans_layer.cpp
+++ b/core/sip/trans_layer.cpp
@@ -1140,7 +1140,7 @@ static int generate_and_parse_new_msg(sip_msg* msg, sip_msg*& p_msg)
     request_len += copy_hdrs_len_no_via_contact(msg->hdrs);
     request_len += copy_hdrs_len(n_contacts);
 
-    string content_len = int2str((unsigned int) msg->body.length());
+    string content_len = int2str(msg->body.length());
 
     request_len += content_length_len(stl2cstr(content_len));
     request_len += 2/* CRLF end-of-headers*/;