diff --git a/src/test/app/LedgerReplay_test.cpp b/src/test/app/LedgerReplay_test.cpp
index 8bf1a8f668..229cad21c9 100644
--- a/src/test/app/LedgerReplay_test.cpp
+++ b/src/test/app/LedgerReplay_test.cpp
@@ -491,8 +491,7 @@ struct LedgerServer
         for (int i = 0; i < newTxes; ++i)
         {
             updateIdx();
-            env.apply(
-                pay(accounts[fromIdx],
+            env(pay(accounts[fromIdx],
                     accounts[toIdx],
                     jtx::drops(ledgerMaster.getClosedLedger()->fees().base) + jtx::XRP(param.txAmount)),
                 jtx::seq(jtx::autofill),
diff --git a/src/test/jtx/Env.h b/src/test/jtx/Env.h
index ef6240d48a..7d7dcd2cb8 100644
--- a/src/test/jtx/Env.h
+++ b/src/test/jtx/Env.h
@@ -31,6 +31,7 @@
 #include <xrpl/protocol/STTx.h>
 
 #include <functional>
+#include <source_location>
 #include <string>
 #include <tuple>
 #include <type_traits>
@@ -42,6 +43,27 @@ namespace xrpl {
 namespace test {
 namespace jtx {
 
+/** Wrapper that captures std::source_location when implicitly constructed.
+    This solves the problem of combining std::source_location with variadic
+    templates. The std::source_location default argument is evaluated at the
+    call site when the wrapper is constructed via implicit conversion.
+
+    This is a template struct that holds the value directly, allowing implicit
+    conversion without template argument deduction issues via CTAD.
+*/
+template <class T>
+struct WithSourceLocation
+{
+    T value;
+    std::source_location loc;
+
+    // Non-explicit constructor allows implicit conversion.
+    // The default argument for loc is evaluated at the call site.
+    WithSourceLocation(T v, std::source_location l = std::source_location::current()) : value(std::move(v)), loc(l)
+    {
+    }
+};
+
 /** Designate accounts as no-ripple in Env::fund */
 template <class... Args>
 std::array<Account, 1 + sizeof...(Args)>
@@ -522,35 +544,57 @@ public:
         This calls postconditions.
     */
     virtual void
-    submit(JTx const& jt);
+    submit(JTx const& jt, std::source_location const& loc = std::source_location::current());
 
     /** Use the submit RPC command with a provided JTx object.
         This calls postconditions.
     */
     void
-    sign_and_submit(JTx const& jt, Json::Value params = Json::nullValue);
+    sign_and_submit(
+        JTx const& jt,
+        Json::Value params = Json::nullValue,
+        std::source_location const& loc = std::source_location::current());
 
     /** Check expected postconditions
         of JTx submission.
     */
     void
-    postconditions(JTx const& jt, ParsedResult const& parsed, Json::Value const& jr = Json::Value());
+    postconditions(
+        JTx const& jt,
+        ParsedResult const& parsed,
+        Json::Value const& jr = Json::Value(),
+        std::source_location const& loc = std::source_location::current());
 
     /** Apply funclets and submit. */
     /** @{ */
-    template <class JsonValue, class... FN>
+    template <class... FN>
     Env&
-    apply(JsonValue&& jv, FN const&... fN)
+    apply(WithSourceLocation<Json::Value> jv, FN const&... fN)
     {
-        submit(jt(std::forward<JsonValue>(jv), fN...));
+        submit(jt(std::move(jv.value), fN...), jv.loc);
         return *this;
     }
 
-    template <class JsonValue, class... FN>
+    template <class... FN>
     Env&
-    operator()(JsonValue&& jv, FN const&... fN)
+    apply(WithSourceLocation<JTx> jv, FN const&... fN)
     {
-        return apply(std::forward<JsonValue>(jv), fN...);
+        submit(jt(std::move(jv.value), fN...), jv.loc);
+        return *this;
+    }
+
+    template <class... FN>
+    Env&
+    operator()(WithSourceLocation<Json::Value> jv, FN const&... fN)
+    {
+        return apply(std::move(jv), fN...);
+    }
+
+    template <class... FN>
+    Env&
+    operator()(WithSourceLocation<JTx> jv, FN const&... fN)
+    {
+        return apply(std::move(jv), fN...);
     }
     /** @} */
 
diff --git a/src/test/jtx/Env_ss.h b/src/test/jtx/Env_ss.h
index 78146a04a4..9c178a1c13 100644
--- a/src/test/jtx/Env_ss.h
+++ b/src/test/jtx/Env_ss.h
@@ -23,19 +23,20 @@ private:
         SignSubmitRunner&
         operator=(SignSubmitRunner&&) = delete;
 
-        SignSubmitRunner(Env& env, JTx&& jt) : env_(env), jt_(jt)
+        SignSubmitRunner(Env& env, JTx&& jt, std::source_location loc) : env_(env), jt_(jt), loc_(loc)
         {
         }
 
         void
         operator()(Json::Value const& params = Json::nullValue)
         {
-            env_.sign_and_submit(jt_, params);
+            env_.sign_and_submit(jt_, params, loc_);
         }
 
     private:
         Env& env_;
         JTx const jt_;
+        std::source_location const loc_;
     };
 
 public:
@@ -47,12 +48,20 @@ public:
     {
     }
 
-    template <class JsonValue, class... FN>
+    template <class... FN>
     SignSubmitRunner
-    operator()(JsonValue&& jv, FN const&... fN)
+    operator()(WithSourceLocation<Json::Value> jv, FN const&... fN)
     {
-        auto jtx = env_.jt(std::forward<JsonValue>(jv), fN...);
-        return SignSubmitRunner(env_, std::move(jtx));
+        auto jtx = env_.jt(std::move(jv.value), fN...);
+        return SignSubmitRunner(env_, std::move(jtx), jv.loc);
+    }
+
+    template <class... FN>
+    SignSubmitRunner
+    operator()(WithSourceLocation<JTx> jv, FN const&... fN)
+    {
+        auto jtx = env_.jt(std::move(jv.value), fN...);
+        return SignSubmitRunner(env_, std::move(jtx), jv.loc);
     }
 };
 
diff --git a/src/test/jtx/impl/Env.cpp b/src/test/jtx/impl/Env.cpp
index 9971da05c4..d8bcec84ee 100644
--- a/src/test/jtx/impl/Env.cpp
+++ b/src/test/jtx/impl/Env.cpp
@@ -27,6 +27,7 @@
 #include <xrpl/protocol/jss.h>
 
 #include <memory>
+#include <source_location>
 
 namespace xrpl {
 namespace test {
@@ -330,7 +331,7 @@ Env::parseResult(Json::Value const& jr)
 }
 
 void
-Env::submit(JTx const& jt)
+Env::submit(JTx const& jt, std::source_location const& loc)
 {
     ParsedResult parsedResult;
     auto const jr = [&]() {
@@ -356,11 +357,11 @@ Env::submit(JTx const& jt)
             return Json::Value();
         }
     }();
-    return postconditions(jt, parsedResult, jr);
+    return postconditions(jt, parsedResult, jr, loc);
 }
 
 void
-Env::sign_and_submit(JTx const& jt, Json::Value params)
+Env::sign_and_submit(JTx const& jt, Json::Value params, std::source_location const& loc)
 {
     auto const account = lookup(jt.jv[jss::Account].asString());
     auto const& passphrase = account.name();
@@ -393,25 +394,26 @@ Env::sign_and_submit(JTx const& jt, Json::Value params)
     test.expect(parsedResult.ter, "ter uninitialized!");
     ter_ = parsedResult.ter.value_or(telENV_RPC_FAILED);
 
-    return postconditions(jt, parsedResult, jr);
+    return postconditions(jt, parsedResult, jr, loc);
 }
 
 void
-Env::postconditions(JTx const& jt, ParsedResult const& parsed, Json::Value const& jr)
+Env::postconditions(JTx const& jt, ParsedResult const& parsed, Json::Value const& jr, std::source_location const& loc)
 {
     auto const line = jt.testLine ? " (" + to_string(*jt.testLine) + ")" : "";
-    bool bad = !test.expect(parsed.ter, "apply: No ter result!" + line);
+    auto const locStr = std::string("(") + loc.file_name() + ":" + to_string(loc.line()) + ")";
+    bool bad = !test.expect(parsed.ter, "apply " + locStr + ": No ter result!" + line);
     bad =
         (jt.ter && parsed.ter &&
          !test.expect(
              *parsed.ter == *jt.ter,
-             "apply: Got " + transToken(*parsed.ter) + " (" + transHuman(*parsed.ter) + "); Expected " +
+             "apply " + locStr + ": Got " + transToken(*parsed.ter) + " (" + transHuman(*parsed.ter) + "); Expected " +
                  transToken(*jt.ter) + " (" + transHuman(*jt.ter) + ")" + line));
     using namespace std::string_literals;
     bad = (jt.rpcCode &&
            !test.expect(
                parsed.rpcCode == jt.rpcCode->first && parsed.rpcMessage == jt.rpcCode->second,
-               "apply: Got RPC result "s +
+               "apply " + locStr + ": Got RPC result "s +
                    (parsed.rpcCode ? RPC::get_error_info(*parsed.rpcCode).token.c_str() : "NO RESULT") + " (" +
                    parsed.rpcMessage + "); Expected " + RPC::get_error_info(jt.rpcCode->first).token.c_str() + " (" +
                    jt.rpcCode->second + ")" + line)) ||
@@ -419,13 +421,14 @@ Env::postconditions(JTx const& jt, ParsedResult const& parsed, Json::Value const
     // If we have an rpcCode (just checked), then the rpcException check is
     // optional - the 'error' field may not be defined, but if it is, it must
     // match rpcError.
-    bad = (jt.rpcException &&
-           !test.expect(
-               (jt.rpcCode && parsed.rpcError.empty()) ||
-                   (parsed.rpcError == jt.rpcException->first &&
-                    (!jt.rpcException->second || parsed.rpcException == *jt.rpcException->second)),
-               "apply: Got RPC result "s + parsed.rpcError + " (" + parsed.rpcException + "); Expected " +
-                   jt.rpcException->first + " (" + jt.rpcException->second.value_or("n/a") + ")" + line)) ||
+    bad =
+        (jt.rpcException &&
+         !test.expect(
+             (jt.rpcCode && parsed.rpcError.empty()) ||
+                 (parsed.rpcError == jt.rpcException->first &&
+                  (!jt.rpcException->second || parsed.rpcException == *jt.rpcException->second)),
+             "apply " + locStr + ": Got RPC result "s + parsed.rpcError + " (" + parsed.rpcException + "); Expected " +
+                 jt.rpcException->first + " (" + jt.rpcException->second.value_or("n/a") + ")" + line)) ||
         bad;
     if (bad)
     {
diff --git a/src/test/rpc/Subscribe_test.cpp b/src/test/rpc/Subscribe_test.cpp
index 4f83f81da5..cce45fb4ef 100644
--- a/src/test/rpc/Subscribe_test.cpp
+++ b/src/test/rpc/Subscribe_test.cpp
@@ -835,8 +835,7 @@ public:
             {
                 auto& from = (i % 2 == 0) ? a : b;
                 auto& to = (i % 2 == 0) ? b : a;
-                env.apply(
-                    pay(from, to, jtx::XRP(numXRP)),
+                env(pay(from, to, jtx::XRP(numXRP)),
                     jtx::seq(jtx::autofill),
                     jtx::fee(jtx::autofill),
                     jtx::sig(jtx::autofill));