diff --git a/src/utils.cpp b/src/utils.cpp
index 296915981a..745cb72b56 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -109,14 +109,11 @@ std::string utils::getsyserror()
   return std::string(strerror(errno));
 }
 
-/** \brief try to detect pathname from FILE pointer. Currently only supported on Linux, otherwise will report "(unknown)".
- *
- *  \param buf  storage buffer for pathname. output will be truncated if not large enough
- *  \param len  size of storage buffer. output will be truncated to this length - 1
- *  \param fp   FILE pointer structe from STDIO library for which we want to detect the name
- *  \return pointer to the storage buffer, i.e. buf
+/*
+ * On Linux the folder /proc/self/fd holds symbolic links to the actual
+ * pathnames associated with each open file descriptor of the current process.
  */
-static const char *guesspath(char *buf, int len, FILE *fp)
+const char *utils::guesspath(char *buf, int len, FILE *fp)
 {
   memset(buf,0,len);
 
@@ -124,9 +121,9 @@ static const char *guesspath(char *buf, int len, FILE *fp)
   int fd = fileno(fp);
   // get pathname from /proc or copy (unknown)
   if (readlink(fmt::format("/proc/self/fd/{}",fd).c_str(),buf,len-1) <= 0)
-    strcpy(buf,"(unknown)");
+    strncpy(buf,"(unknown)",len-1);
 #else
-  strcpy(buf,"(unknown)");
+  strncpy(buf,"(unknown)",len-1);
 #endif
   return buf;
 }
diff --git a/src/utils.h b/src/utils.h
index 047f6be296..abaa87ca5f 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -210,6 +210,17 @@ namespace LAMMPS_NS {
      */
     bool is_double(const std::string & str);
 
+    /** \brief try to detect pathname from FILE pointer.
+     *
+     * Currently only supported on Linux, otherwise will report "(unknown)".
+     *
+     *  \param buf  storage buffer for pathname. output will be truncated if not large enough
+     *  \param len  size of storage buffer. output will be truncated to this length - 1
+     *  \param fp   FILE pointer structe from STDIO library for which we want to detect the name
+     *  \return pointer to the storage buffer, i.e. buf
+     */
+    const char *guesspath(char *buf, int len, FILE *fp);
+
     /**
      * \brief Strip off leading part of path, return just the filename
      * \param path file path
diff --git a/unittest/utils/test_utils.cpp b/unittest/utils/test_utils.cpp
index c4b4042bf9..8e23f7dd97 100644
--- a/unittest/utils/test_utils.cpp
+++ b/unittest/utils/test_utils.cpp
@@ -22,6 +22,7 @@
 
 using namespace LAMMPS_NS;
 using ::testing::Eq;
+using ::testing::EndsWith;
 
 TEST(Utils, trim_comment)
 {
@@ -277,6 +278,20 @@ TEST(Utils, strmatch_opt_range)
     ASSERT_TRUE(utils::strmatch("rigid", "^[0-9]*[p-s]igid"));
 }
 
+TEST(Utils, guesspath)
+{
+    char buf[128];
+    FILE *fp = fopen("test_guesspath.txt","w");
+#if defined(__linux__)
+    const char *path = utils::guesspath(buf,sizeof(buf),fp);
+    ASSERT_THAT(path,EndsWith("test_guesspath.txt"));
+#else
+    const char *path = utils::guesspath(buf,sizeof(buf),fp);
+    ASSERT_THAT(path,EndsWith("(unknown)"));
+#endif
+    fclose(fp);
+}
+
 TEST(Utils, path_join)
 {
 #if defined(_WIN32)