diff --git a/src/dump.cpp b/src/dump.cpp
index 031364dada..c483d90fc3 100644
--- a/src/dump.cpp
+++ b/src/dump.cpp
@@ -14,16 +14,16 @@
 #include "dump.h"
 
 #include "atom.h"
-#include "irregular.h"
-#include "update.h"
-#include "domain.h"
-#include "group.h"
-#include "output.h"
-#include "modify.h"
-#include "fix.h"
 #include "compute.h"
-#include "memory.h"
+#include "domain.h"
 #include "error.h"
+#include "fix.h"
+#include "group.h"
+#include "irregular.h"
+#include "memory.h"
+#include "modify.h"
+#include "output.h"
+#include "update.h"
 
 #include <cstring>
 
@@ -141,12 +141,9 @@ Dump::Dump(LAMMPS *lmp, int /*narg*/, char **arg) : Pointers(lmp)
 
   if (strchr(filename,'*')) multifile = 1;
 
-  char *suffix = filename + strlen(filename) - strlen(".bin");
-  if (suffix > filename && strcmp(suffix,".bin") == 0) binary = 1;
-  suffix = filename + strlen(filename) - strlen(".gz");
-  if (suffix > filename && strcmp(suffix,".gz") == 0) compressed = 1;
-  suffix = filename + strlen(filename) - strlen(".zst");
-  if (suffix > filename && strcmp(suffix,".zst") == 0) compressed = 1;
+  if (utils::strmatch(filename, "\\.bin$")) binary = 1;
+  if (utils::strmatch(filename, "\\.gz$")
+      || utils::strmatch(filename, "\\.zst$")) compressed = 1;
 }
 
 /* ---------------------------------------------------------------------- */
@@ -582,12 +579,11 @@ void Dump::openfile()
   if (filewriter) {
     if (compressed) {
 #ifdef LAMMPS_GZIP
-      char gzip[128];
-      sprintf(gzip,"gzip -6 > %s",filecurrent);
+      auto gzip = fmt::format("gzip -6 > {}",filecurrent);
 #ifdef _WIN32
-      fp = _popen(gzip,"wb");
+      fp = _popen(gzip.c_str(),"wb");
 #else
-      fp = popen(gzip,"w");
+      fp = popen(gzip.c_str(),"w");
 #endif
 #else
       error->one(FLERR,"Cannot open gzipped file");
diff --git a/src/fix_tmd.cpp b/src/fix_tmd.cpp
index 8cff132c63..f462b0633b 100644
--- a/src/fix_tmd.cpp
+++ b/src/fix_tmd.cpp
@@ -18,19 +18,18 @@
 
 #include "fix_tmd.h"
 
+#include "atom.h"
+#include "domain.h"
+#include "error.h"
+#include "force.h"
+#include "group.h"
+#include "memory.h"
+#include "modify.h"
+#include "respa.h"
+#include "update.h"
+
 #include <cmath>
 #include <cstring>
-#include "atom.h"
-#include "update.h"
-#include "modify.h"
-#include "domain.h"
-#include "group.h"
-#include "respa.h"
-#include "force.h"
-#include "memory.h"
-#include "error.h"
-
-
 
 using namespace LAMMPS_NS;
 using namespace FixConst;
@@ -520,31 +519,29 @@ void FixTMD::readfile(char *file)
 
 void FixTMD::open(char *file)
 {
-  compressed = 0;
-  char *suffix = file + strlen(file) - 3;
-  if (suffix > file && strcmp(suffix,".gz") == 0) compressed = 1;
-  if (!compressed) fp = fopen(file,"r");
-  else {
+  if (utils::strmatch(file,"\\.gz$")) {
+    compressed = 1;
+
 #ifdef LAMMPS_GZIP
-    char gunzip[128];
-    snprintf(gunzip,128,"gzip -c -d %s",file);
+    auto gunzip = fmt::format("gzip -c -d {}",file);
 
 #ifdef _WIN32
-    fp = _popen(gunzip,"rb");
+    fp = _popen(gunzip.c_str(),"rb");
 #else
-    fp = popen(gunzip,"r");
+    fp = popen(gunzip.c_str(),"r");
 #endif
 
 #else
-    error->one(FLERR,"Cannot open gzipped file");
+    error->one(FLERR,"Cannot open gzipped file without gzip support");
 #endif
+  } else {
+    compressed = 0;
+    fp = fopen(file,"r");
   }
 
-  if (fp == nullptr) {
-    char str[128];
-    snprintf(str,128,"Cannot open file %s",file);
-    error->one(FLERR,str);
-  }
+  if (fp == nullptr)
+    error->one(FLERR,fmt::format("Cannot open file {}: {}",
+                                 file, utils::getsyserror()));
 }
 
 /* ---------------------------------------------------------------------- */
diff --git a/src/library.cpp b/src/library.cpp
index b72c8d7220..300aafc293 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -4734,19 +4734,14 @@ void lammps_set_fix_external_callback(void *handle, char *id, FixExternalFnPtr c
   BEGIN_CAPTURE
   {
     int ifix = lmp->modify->find_fix(id);
-    if (ifix < 0) {
-      char str[128];
-      snprintf(str, 128, "Can not find fix with ID '%s'!", id);
-      lmp->error->all(FLERR,str);
-    }
+    if (ifix < 0)
+      lmp->error->all(FLERR,fmt::format("Cannot find fix with ID '{}'!", id));
 
     Fix *fix = lmp->modify->fix[ifix];
 
-    if (strcmp("external",fix->style) != 0) {
-      char str[128];
-      snprintf(str, 128, "Fix '%s' is not of style external!", id);
-      lmp->error->all(FLERR,str);
-    }
+    if (strcmp("external",fix->style) != 0)
+      lmp->error->all(FLERR,fmt::format("Fix '{}' is not of style "
+                                        "external!", id));
 
     FixExternal * fext = (FixExternal*) fix;
     fext->set_callback(callback, caller);
diff --git a/src/read_data.cpp b/src/read_data.cpp
index 09fb8f3eae..cc3b2e5965 100644
--- a/src/read_data.cpp
+++ b/src/read_data.cpp
@@ -1954,13 +1954,12 @@ int ReadData::reallocate(int **pcount, int cmax, int amax)
 
 void ReadData::open(char *file)
 {
-  compressed = 0;
-  char *suffix = file + strlen(file) - 3;
-  if (suffix > file && strcmp(suffix,".gz") == 0) compressed = 1;
-  if (!compressed) fp = fopen(file,"r");
-  else {
+  if (utils::strmatch(file,"\\.gz$")) {
+    compressed = 1;
+
 #ifdef LAMMPS_GZIP
-    std::string gunzip = fmt::format("gzip -c -d {}",file);
+    auto gunzip = fmt::format("gzip -c -d {}",file);
+
 #ifdef _WIN32
     fp = _popen(gunzip.c_str(),"rb");
 #else
@@ -1968,8 +1967,11 @@ void ReadData::open(char *file)
 #endif
 
 #else
-    error->one(FLERR,"Cannot open gzipped file: " + utils::getsyserror());
+    error->one(FLERR,"Cannot open gzipped file without gzip support");
 #endif
+  } else {
+    compressed = 0;
+    fp = fopen(file,"r");
   }
 
   if (fp == nullptr)
diff --git a/src/reader.cpp b/src/reader.cpp
index a4bc8d816f..c22a9f7e5d 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -37,13 +37,12 @@ void Reader::open_file(const char *file)
 {
   if (fp != nullptr) close_file();
 
-  compressed = 0;
-  const char *suffix = file + strlen(file) - 3;
-  if (suffix > file && strcmp(suffix,".gz") == 0) compressed = 1;
-  if (!compressed) fp = fopen(file,"r");
-  else {
+  if (utils::strmatch(file,"\\.gz$")) {
+    compressed = 1;
+
 #ifdef LAMMPS_GZIP
-    std::string gunzip = fmt::format("gzip -c -d {}",file);
+    auto gunzip = fmt::format("gzip -c -d {}",file);
+
 #ifdef _WIN32
     fp = _popen(gunzip.c_str(),"rb");
 #else
@@ -51,8 +50,11 @@ void Reader::open_file(const char *file)
 #endif
 
 #else
-    error->one(FLERR,"Cannot open gzipped file: " + utils::getsyserror());
+    error->one(FLERR,"Cannot open gzipped file without gzip support");
 #endif
+  } else {
+    compressed = 0;
+    fp = fopen(file,"r");
   }
 
   if (fp == nullptr)