diff --git a/src/timer.cpp b/src/timer.cpp
index 288ac28f43..c6f6401799 100644
--- a/src/timer.cpp
+++ b/src/timer.cpp
@@ -28,8 +28,8 @@ Timer::Timer(LAMMPS *_lmp) : Pointers(_lmp)
 {
   _level = NORMAL;
   _sync = OFF;
-  _timeout = -1;
-  _s_timeout = -1;
+  _timeout = -1.0;
+  _s_timeout = -1.0;
   _checkfreq = 10;
   _nextcheck = -1;
   this->_stamp(RESET);
@@ -251,7 +251,7 @@ void Timer::modify_params(int narg, char **arg)
 
     // format timeout setting
     std::string timeout = "off";
-    if (_timeout >= 0) {
+    if (_timeout >= 0.0) {
       std::tm tv = fmt::gmtime((std::time_t) _timeout);
       timeout = fmt::format("{:02d}:{:%M:%S}", tv.tm_yday * 24 + tv.tm_hour, tv);
     }
diff --git a/src/timer.h b/src/timer.h
index f7efa5ac64..371a895d1f 100644
--- a/src/timer.h
+++ b/src/timer.h
@@ -110,12 +110,12 @@ class Timer : protected Pointers {
   double previous_cpu;
   double previous_wall;
   double timeout_start;
-  int _level;        // level of detail: off=0,loop=1,normal=2,full=3
-  int _sync;         // if nonzero, synchronize tasks before setting the timer
-  int _timeout;      // max allowed wall time in seconds. infinity if negative
-  int _s_timeout;    // copy of timeout for restoring after a forced timeout
-  int _checkfreq;    // frequency of timeout checking
-  int _nextcheck;    // loop number of next timeout check
+  double _timeout;      // max allowed wall time in seconds. infinity if negative
+  double _s_timeout;    // copy of timeout for restoring after a forced timeout
+  int _level;           // level of detail: off=0,loop=1,normal=2,full=3
+  int _sync;            // if nonzero, synchronize tasks before setting the timer
+  int _checkfreq;       // frequency of timeout checking
+  int _nextcheck;       // loop number of next timeout check
 
   // update one specific timer array
   void _stamp(enum ttype);
diff --git a/src/utils.cpp b/src/utils.cpp
index c760f9ffbf..87c46c47ab 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -1677,7 +1677,7 @@ double utils::timespec2seconds(const std::string &timespec)
   try {
     for (i = 0; i < 3; i++) {
       if (!values.has_next()) break;
-      vals[i] = values.next_int();
+      vals[i] = values.next_double();
     }
   } catch (TokenizerException &) {
     return -1.0;
diff --git a/unittest/utils/test_utils.cpp b/unittest/utils/test_utils.cpp
index 58940f6600..c486d0cf3e 100644
--- a/unittest/utils/test_utils.cpp
+++ b/unittest/utils/test_utils.cpp
@@ -1061,6 +1061,16 @@ TEST(Utils, timespec2seconds_hhmmss)
     ASSERT_DOUBLE_EQ(utils::timespec2seconds("2:10:45"), 7845.0);
 }
 
+TEST(Utils, timespec2seconds_ssfraction)
+{
+    ASSERT_DOUBLE_EQ(utils::timespec2seconds("5.2"), 5.2);
+}
+
+TEST(Utils, timespec2seconds_mmfraction)
+{
+    ASSERT_DOUBLE_EQ(utils::timespec2seconds("2.5:10"), 160.0);
+}
+
 TEST(Utils, timespec2seconds_invalid)
 {
     ASSERT_DOUBLE_EQ(utils::timespec2seconds("2:aa:45"), -1.0);