diff --git a/src/atom.cpp b/src/atom.cpp
index 48fed8bbf8..5c60226cdf 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -1185,6 +1185,7 @@ void Atom::data_atoms(int n, char *buf, tagint id_offset, tagint mol_offset,
           coord[1] >= sublo[1] && coord[1] < subhi[1] &&
           coord[2] >= sublo[2] && coord[2] < subhi[2]) {
         avec->data_atom(xdata,imagedata,values,typestr);
+        typestr = utils::utf8_subst(typestr);
         if (id_offset) tag[nlocal-1] += id_offset;
         if (mol_offset) molecule[nlocal-1] += mol_offset;
         // clang-format on
@@ -1291,7 +1292,7 @@ void Atom::data_bonds(int n, char *buf, int *count, tagint id_offset,
     // Bonds line is: number(ignored), bond type, atomID 1, atomID 2
     if (nwords > 0) {
       if (nwords != 4) error->all(FLERR, "Incorrect format in {}: {}", location, utils::trim(buf));
-      typestr = values[1];
+      typestr = utils::utf8_subst(values[1]);
       atom1 = utils::tnumeric(FLERR, values[2], false, lmp);
       atom2 = utils::tnumeric(FLERR, values[3], false, lmp);
       if (id_offset) {
@@ -1388,7 +1389,7 @@ void Atom::data_angles(int n, char *buf, int *count, tagint id_offset,
     // Angles line is: number(ignored), angle type, atomID 1, atomID 2, atomID 3
     if (nwords > 0) {
       if (nwords != 5) error->all(FLERR, "Incorrect format in {}: {}", location, utils::trim(buf));
-      typestr = values[1];
+      typestr = utils::utf8_subst(values[1]);
       atom1 = utils::tnumeric(FLERR, values[2], false, lmp);
       atom2 = utils::tnumeric(FLERR, values[3], false, lmp);
       atom3 = utils::tnumeric(FLERR, values[4], false, lmp);
@@ -1501,7 +1502,7 @@ void Atom::data_dihedrals(int n, char *buf, int *count, tagint id_offset,
     // Dihedrals line is: number(ignored), bond type, atomID 1, atomID 2, atomID 3, atomID 4
     if (nwords > 0) {
       if (nwords != 6) error->all(FLERR, "Incorrect format in {}: {}", location, utils::trim(buf));
-      typestr = values[1];
+      typestr = utils::utf8_subst(values[1]);
       atom1 = utils::tnumeric(FLERR, values[2], false, lmp);
       atom2 = utils::tnumeric(FLERR, values[3], false, lmp);
       atom3 = utils::tnumeric(FLERR, values[4], false, lmp);
@@ -1633,7 +1634,7 @@ void Atom::data_impropers(int n, char *buf, int *count, tagint id_offset,
     // Impropers line is: number(ignored), bond type, atomID 1, atomID 2, atomID 3, atomID 4
     if (nwords > 0) {
       if (nwords != 6) error->all(FLERR, "Incorrect format in {}: {}", location, utils::trim(buf));
-      typestr = values[1];
+      typestr = utils::utf8_subst(values[1]);
       atom1 = utils::tnumeric(FLERR, values[2], false, lmp);
       atom2 = utils::tnumeric(FLERR, values[3], false, lmp);
       atom3 = utils::tnumeric(FLERR, values[4], false, lmp);
@@ -1934,30 +1935,44 @@ void Atom::set_mass(const char *file, int line, int itype, double value)
 
 void Atom::set_mass(const char *file, int line, int /*narg*/, char **arg)
 {
-  if (mass == nullptr) error->all(file,line, "Cannot set atom mass for atom style {}", atom_style);
+  if (mass == nullptr)
+    error->all(file,line, "Cannot set per-type atom mass for atom style {}", atom_style);
 
-  std::string typestr = utils::trim(arg[0]);
-  if (!isdigit(typestr[0]) && typestr[0] != '*') {
-    int itype = lmap->find(typestr,Atom::ATOM);
-    if (itype == -1) error->all(file,line,"Invalid type for mass set");
-    mass[itype] = utils::numeric(FLERR,arg[1],false,lmp);
-    mass_setflag[itype] = 1;
+  // clang-format on
+  std::string typestr = utils::utf8_subst(utils::trim(arg[0]));
+  switch (utils::is_type(typestr)) {
 
-    if (mass[itype] <= 0.0) error->all(file,line,"Invalid mass value");
-  } else {
-    int lo,hi;
-    utils::bounds(file,line,arg[0],1,ntypes,lo,hi,error);
-    if ((lo < 1) || (hi > ntypes))
-      error->all(file,line,"Invalid type {} for atom mass {}", arg[1]);
+    case 0: {    // numeric
+      int lo, hi;
+      utils::bounds(file, line, typestr.c_str(), 1, ntypes, lo, hi, error);
+      if ((lo < 1) || (hi > ntypes))
+        error->all(file, line, "Invalid atom type {} for atom mass", typestr);
 
-    const double value = utils::numeric(FLERR,arg[1],false,lmp);
-    if (value <= 0.0) error->all(file,line,"Invalid atom mass value {}", value);
+      const double value = utils::numeric(FLERR, arg[1], false, lmp);
+      if (value <= 0.0)
+        error->all(file, line, "Invalid atom mass value {} for type {}", value, typestr);
 
-    for (int itype = lo; itype <= hi; itype++) {
-      mass[itype] = value;
-      mass_setflag[itype] = 1;
+      for (int itype = lo; itype <= hi; itype++) {
+        mass[itype] = value;
+        mass_setflag[itype] = 1;
+      }
+      break;
     }
+
+    case 1: {    // type label
+      if (!atom->labelmapflag) error->all(FLERR, "Invalid atom type {} for setting mass", typestr);
+      int itype = lmap->find(typestr, Atom::ATOM);
+      if (itype == -1) error->all(file, line, "Invalid type {} for setting mass", typestr);
+      mass[itype] = utils::numeric(FLERR, arg[1], false, lmp);
+      mass_setflag[itype] = 1;
+      break;
+    }
+
+    default:    // invalid
+      error->one(FLERR, "Invalid mass setting");
+      break;
   }
+  // clang-format off
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/atom_vec.cpp b/src/atom_vec.cpp
index b254575d88..c11bbe16b0 100644
--- a/src/atom_vec.cpp
+++ b/src/atom_vec.cpp
@@ -1666,7 +1666,8 @@ void AtomVec::data_atom(double *coord, imageint imagetmp, const std::vector<std:
    initialize other peratom quantities
 ------------------------------------------------------------------------- */
 
-void AtomVec::data_atom(double *coord, imageint imagetmp, const std::vector<std::string> &values, std::string &extract)
+void AtomVec::data_atom(double *coord, imageint imagetmp, const std::vector<std::string> &values,
+                        std::string &extract)
 {
   int m, n, datatype, cols;
   void *pdata;
diff --git a/src/label_map.cpp b/src/label_map.cpp
index ffa496fbcc..8e842320ad 100644
--- a/src/label_map.cpp
+++ b/src/label_map.cpp
@@ -141,7 +141,7 @@ void LabelMap::modify_lmap(int narg, char **arg)
     int itype = utils::inumeric(FLERR, arg[iarg++], false, lmp);
     if ((itype < 1) || (itype > ntypes))
       error->all(FLERR, "Labelmap {} type {} must be within 1-{}", tlabel, itype, ntypes);
-    std::string slabel = utils::trim(arg[iarg++]);
+    std::string slabel = utils::utf8_subst(utils::trim(arg[iarg++]));
     if (utils::is_type(slabel) != 1)
       error->all(FLERR, "Type label string {} for {} type {} is invalid", slabel, tlabel, itype);
     int found = search(slabel, (*labels_map));
diff --git a/src/read_data.cpp b/src/read_data.cpp
index 85324947fe..23fac2c922 100644
--- a/src/read_data.cpp
+++ b/src/read_data.cpp
@@ -2159,6 +2159,7 @@ void ReadData::typelabels(int mode)
     }
     if (nwords != 2)
       error->all(FLERR, "Invalid format in section: {} Type Labels: {}", labeltypes[mode], buf);
+    values[1] = utils::utf8_subst(values[1]);
     if (utils::is_type(values[1]) != 1) error->all(FLERR, "Invalid type label {}", values[1]);
     int itype = utils::inumeric(FLERR, values[0], false, lmp);
     if ((itype < 1) || (itype > lntypes))
diff --git a/src/utils.cpp b/src/utils.cpp
index c11ae8433c..5ae367729f 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -1162,8 +1162,10 @@ int utils::is_type(const std::string &str)
   // TODO: the first two checks below are not really needed with this function.
   // If a type label has at least one character that is not a digit or '*'
   // it can be identified by this function as type label due to the check above.
+  // Whitespace and multi-byte characters are not allowed.
   if (isdigit(str[0]) || (str[0] == '*') || (str[0] == '#')) return -1;
   if (str.find_first_of(" \t\r\n\f") != std::string::npos) return -1;
+  if (has_utf8(utf8_subst(str))) return -1;
   return 1;
 }
 
diff --git a/unittest/commands/test_labelmap.cpp b/unittest/commands/test_labelmap.cpp
index dcb2559550..baa29f6f36 100644
--- a/unittest/commands/test_labelmap.cpp
+++ b/unittest/commands/test_labelmap.cpp
@@ -64,18 +64,28 @@ TEST_F(SetTest, NoBoxAtoms)
     command("create_box 4 box");
     command("labelmap atom 2 N1");
     command("labelmap atom 3 O1 4 H1");
+    command("mass * 1.0");
+    command("mass O1 3.0");
+    command("mass N1 2.0");
+    command("mass H1 4.0");
     END_HIDE_OUTPUT();
     ASSERT_NE(atom->lmap, nullptr);
     ASSERT_FALSE(atom->lmap->is_complete(Atom::ATOM));
+    ASSERT_DOUBLE_EQ(atom->mass[1], 1.0);
+    ASSERT_DOUBLE_EQ(atom->mass[2], 2.0);
+    ASSERT_DOUBLE_EQ(atom->mass[3], 3.0);
+    ASSERT_DOUBLE_EQ(atom->mass[4], 4.0);
 
     BEGIN_HIDE_OUTPUT();
     command("labelmap atom 1 C1 2 N2 3 ' O#' 1 C1 4 H# 2 N3"); // second '#' starts comment
+    command("mass \"O#\" 10.0");
     END_HIDE_OUTPUT();
     ASSERT_TRUE(atom->lmap->is_complete(Atom::ATOM));
     ASSERT_EQ(atom->lmap->find("C1", Atom::ATOM), 1);
     ASSERT_EQ(atom->lmap->find("N2", Atom::ATOM), 2);
     ASSERT_EQ(atom->lmap->find("O#", Atom::ATOM), 3);
     ASSERT_EQ(atom->lmap->find("H", Atom::ATOM), 4);
+    ASSERT_DOUBLE_EQ(atom->mass[3], 10.0);
 
     TEST_FAILURE(".*ERROR: Labelmap atom type 0 must be within 1-4.*",
                  command("labelmap atom 0 C1"););
diff --git a/unittest/utils/test_utils.cpp b/unittest/utils/test_utils.cpp
index 7cadcfdb5a..cff7375aeb 100644
--- a/unittest/utils/test_utils.cpp
+++ b/unittest/utils/test_utils.cpp
@@ -141,8 +141,8 @@ TEST(Utils, count_words_with_extra_spaces)
 
 TEST(Utils, join_words)
 {
-    std::vector<std::string> words = {"one", "two", "three" };
-    auto combined = utils::join_words(words, " ");
+    std::vector<std::string> words = {"one", "two", "three"};
+    auto combined                  = utils::join_words(words, " ");
     ASSERT_THAT(combined, StrEq("one two three"));
     combined = utils::join_words(words, "");
     ASSERT_THAT(combined, StrEq("onetwothree"));
@@ -469,6 +469,8 @@ TEST(Utils, valid_label)
     ASSERT_EQ(utils::is_type("@X2=&X1"), 1);
     ASSERT_EQ(utils::is_type("|Na|Cl|H2O|"), 1);
     ASSERT_EQ(utils::is_type("CA(1)/CB(1)"), 1);
+    ASSERT_EQ(utils::is_type("A-B"), 1); // ASCII
+    ASSERT_EQ(utils::is_type("A−B"), 1); // UTF-8
 }
 
 TEST(Utils, invalid_label)