diff --git a/planning/src/RS/rsCheck.cpp b/planning/src/RS/rsCheck.cpp
index 3973bc90..67220c7d 100644
--- a/planning/src/RS/rsCheck.cpp
+++ b/planning/src/RS/rsCheck.cpp
@@ -1,6 +1,7 @@
 #include "RS/rsCheck.h"
 #include "file_io/pln_blif_file.h"
 #include "file_io/pln_csv_reader.h"
+#include <filesystem>
 
 namespace pln {
 
@@ -117,8 +118,13 @@ bool do_check_blif(CStr cfn,
       lprintf("  # WARNINGS= %u", numWarn);
     lputs();
     if (numWarn or ::getenv("pln_always_write_blif")) {
-      string outFn = str::concat("PLN_W", std::to_string(numWarn), "_", cfn);
+      std::filesystem::path full_path{bfile.fnm_};
+      std::filesystem::path base_path = full_path.filename();
+      std::string base = base_path.string();
+      string outFn = str::concat("PLN_W", std::to_string(numWarn), "_", base);
+
       string wr_ok = bfile.writeBlif(outFn, numWarn);
+
       if (wr_ok.empty())
         lprintf("---!!  FAILED writeBlif to '%s'\n", outFn.c_str());
       else
diff --git a/planning/src/file_io/pln_blif_file.cpp b/planning/src/file_io/pln_blif_file.cpp
index 947de344..fa2612d7 100644
--- a/planning/src/file_io/pln_blif_file.cpp
+++ b/planning/src/file_io/pln_blif_file.cpp
@@ -306,7 +306,7 @@ bool BLIF_file::readBlif() noexcept {
   }
 
   size_t num_escaped = escapeNL();
-  if (trace_ >= 4) {
+  if (trace_ >= 6) {
     lprintf(" ....\\ ...  num_escaped= %zu\n", num_escaped);
   }
 
@@ -2509,7 +2509,12 @@ string BLIF_file::writeBlif(const string& toFn, bool cleanUp) noexcept {
   if (not hasLines())
     return {};
 
-  string fn2 = (toFn == fnm_ ? str::concat("2_", toFn) : toFn);
+  string fn2 = toFn; // (toFn == fnm_ ? str::concat("2_", toFn) : toFn);
+
+  if (trace_ >= 4) {
+    lout() << "pln_blif_file: writing BLIF to " << fn2
+           << "\n  CWD= " << get_CWD() << endl;
+  }
 
   CStr cnm = fn2.c_str();
   FILE* f = ::fopen(cnm, "w");
@@ -2562,7 +2567,7 @@ string BLIF_file::writeBlif(const string& toFn, bool cleanUp) noexcept {
         buf[0] = 0; buf[1] = 0;
         size_t rdsz = dNode.realData_.size();
         if (trace_ >= 4) {
-          lprintf("wrBlif: cell %s at line %zu has dangling bit, filtering..\n",
+          lprintf("  wrBlif: cell %s at line %zu has dangling bit, filtering..\n",
                   dNode.cPrimType(), lineNum);
           if (trace_ >= 5) {
             lprintf("    dangling cell realData_.size()= %zu\n", rdsz);
@@ -2581,7 +2586,7 @@ string BLIF_file::writeBlif(const string& toFn, bool cleanUp) noexcept {
           tail = ::stpcpy(tail, ts);
         }
         if (trace_ >= 4) {
-          lprintf("wrBlif: filtered dangling bits (%u) for cell %s at line %zu\n",
+          lprintf("  wrBlif: filtered dangling bits (%u) for cell %s at line %zu\n",
                   skipCnt, dNode.cPrimType(), lineNum);
         }
       }
@@ -2617,6 +2622,8 @@ string BLIF_file::writeBlif(const string& toFn, bool cleanUp) noexcept {
 
   flush_out(trace_ >= 5);
 
+  if (error)
+    return {};
   return fn2;
 }
 
diff --git a/planning/src/main.cpp b/planning/src/main.cpp
index e505da56..4701aa5d 100644
--- a/planning/src/main.cpp
+++ b/planning/src/main.cpp
@@ -1,4 +1,4 @@
-static const char* _pln_VERSION_STR = "pln0355";
+static const char* _pln_VERSION_STR = "pln0356";
 
 #include "RS/rsEnv.h"
 #include "util/pln_log.h"
diff --git a/planning/src/util/pln_log.h b/planning/src/util/pln_log.h
index b7ca5c59..7a6fb2f1 100644
--- a/planning/src/util/pln_log.h
+++ b/planning/src/util/pln_log.h
@@ -156,10 +156,18 @@ inline string concat(CStr a, const string& b, CStr c, CStr d) noexcept {
   if (a)
     z = a;
   z += b;
-  if (c)
-    z += c;
-  if (d)
-    z += d;
+  if (c) z += c;
+  if (d) z += d;
+  return z;
+}
+inline string concat(CStr a, const string& b, CStr c, const string& d) noexcept {
+  string z;
+  z.reserve(p_strlen(a) + b.length() + p_strlen(c) + d.length() + 1);
+  if (a)
+    z = a;
+  z += b;
+  if (c) z += c;
+  z += d;
   return z;
 }
 inline string concat(const string& a, CStr b) noexcept { return b ? a + b : a; }