diff --git a/src/utils.cpp b/src/utils.cpp
index d9320f464e..7bb157afe5 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -851,7 +851,7 @@ std::vector<std::string> utils::split_words(const std::string &text)
 ------------------------------------------------------------------------- */
 
 bool utils::is_integer(const std::string &str) {
-  if (str.size() == 0) {
+  if (str.empty()) {
     return false;
   }
 
@@ -867,7 +867,7 @@ bool utils::is_integer(const std::string &str) {
 ------------------------------------------------------------------------- */
 
 bool utils::is_double(const std::string &str) {
-  if (str.size() == 0) {
+  if (str.empty()) {
     return false;
   }
 
@@ -880,6 +880,22 @@ bool utils::is_double(const std::string &str) {
   return true;
 }
 
+/* ----------------------------------------------------------------------
+   Return whether string is a valid ID string
+------------------------------------------------------------------------- */
+
+bool utils::is_id(const std::string &str) {
+  if (str.empty()) {
+    return false;
+  }
+
+  for (auto c : str) {
+    if (isalnum(c) || (c == '_')) continue;
+    return false;
+  }
+  return true;
+}
+
 /* ----------------------------------------------------------------------
    strip off leading part of path, return just the filename
 ------------------------------------------------------------------------- */
diff --git a/src/utils.h b/src/utils.h
index 70a4c08cd3..eab81f1343 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -335,6 +335,14 @@ namespace LAMMPS_NS {
 
     bool is_double(const std::string &str);
 
+    /** Check if string is a valid ID
+     * ID strings may contain only letters, numbers, and underscores.
+     *
+     * \param str string that should be checked
+     * \return true, if string contains valid id, false otherwise */
+
+    bool is_id(const std::string &str);
+
     /** Try to detect pathname from FILE pointer.
      *
      * Currently only supported on Linux, otherwise will report "(unknown)".
diff --git a/unittest/utils/test_utils.cpp b/unittest/utils/test_utils.cpp
index a0e4022d2c..5b509318c9 100644
--- a/unittest/utils/test_utils.cpp
+++ b/unittest/utils/test_utils.cpp
@@ -287,6 +287,61 @@ TEST(Utils, signed_double_and_d_exponential)
     ASSERT_FALSE(utils::is_double("-10D-22"));
 }
 
+TEST(Utils, valid_id1)
+{
+    ASSERT_TRUE(utils::is_id("abc"));
+}
+
+TEST(Utils, valid_id2)
+{
+    ASSERT_TRUE(utils::is_id("123"));
+}
+
+TEST(Utils, valid_id3)
+{
+    ASSERT_TRUE(utils::is_id("abc123"));
+}
+
+TEST(Utils, valid_id4)
+{
+    ASSERT_TRUE(utils::is_id("abc_123"));
+}
+
+TEST(Utils, valid_id5)
+{
+    ASSERT_TRUE(utils::is_id("123_abc"));
+}
+
+TEST(Utils, valid_id6)
+{
+    ASSERT_TRUE(utils::is_id("_123"));
+}
+
+TEST(Utils, valid_id7)
+{
+    ASSERT_TRUE(utils::is_id("___"));
+}
+
+TEST(Utils, invalid_id1)
+{
+    ASSERT_FALSE(utils::is_id("+abc"));
+}
+
+TEST(Utils, invalid_id2)
+{
+    ASSERT_FALSE(utils::is_id("a[1]"));
+}
+
+TEST(Utils, invalid_id3)
+{
+    ASSERT_FALSE(utils::is_id("b(c)"));
+}
+
+TEST(Utils, invalid_id4)
+{
+    ASSERT_FALSE(utils::is_id("a$12"));
+}
+
 TEST(Utils, strmatch_beg)
 {
     ASSERT_TRUE(utils::strmatch("rigid/small/omp", "^rigid"));