diff --git a/src/utils.cpp b/src/utils.cpp
index 81d886f3ed..eabe86adbc 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -422,7 +422,7 @@ int utils::inumeric(const char *file, int line, const std::string &str, bool do_
    wrapper for inumeric() that accepts a char pointer instead of a string
 ------------------------------------------------------------------------- */
 
-double utils::inumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
+int utils::inumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
 {
   if (str)
     return inumeric(file, line, std::string(str), do_abort, lmp);
@@ -467,7 +467,7 @@ bigint utils::bnumeric(const char *file, int line, const std::string &str, bool
    wrapper for bnumeric() that accepts a char pointer instead of a string
 ------------------------------------------------------------------------- */
 
-double utils::bnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
+bigint utils::bnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
 {
   if (str)
     return bnumeric(file, line, std::string(str), do_abort, lmp);
@@ -512,7 +512,7 @@ tagint utils::tnumeric(const char *file, int line, const std::string &str, bool
    wrapper for tnumeric() that accepts a char pointer instead of a string
 ------------------------------------------------------------------------- */
 
-double utils::tnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
+tagint utils::tnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
 {
   if (str)
     return tnumeric(file, line, std::string(str), do_abort, lmp);
diff --git a/src/utils.h b/src/utils.h
index 4a8080e2ba..47a4ace5f9 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -226,7 +226,7 @@ namespace utils {
    *  \param lmp      pointer to top-level LAMMPS class instance
    *  \return         double precision floating point number */
 
-  double inumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp);
+  int inumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp);
 
   /*! Convert a string to an integer number while checking
    *  if it is a valid integer number (bigint)
@@ -249,7 +249,7 @@ namespace utils {
    *  \param lmp      pointer to top-level LAMMPS class instance
    *  \return         double precision floating point number */
 
-  double bnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp);
+  bigint bnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp);
 
   /*! Convert a string to an integer number while checking
    *  if it is a valid integer number (tagint)
@@ -272,7 +272,7 @@ namespace utils {
    *  \param lmp      pointer to top-level LAMMPS class instance
    *  \return         double precision floating point number */
 
-  double tnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp);
+  tagint tnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp);
 
   /*! Compute index bounds derived from a string with a possible wildcard
    *