diff --git a/f90/UTILS/ModEM_getrusage.c b/f90/UTILS/ModEM_getrusage.c
index edd61e0a..5056c49e 100644
--- a/f90/UTILS/ModEM_getrusage.c
+++ b/f90/UTILS/ModEM_getrusage.c
@@ -12,27 +12,28 @@
 * To call this C function from Fortran, use this interface:
 *
 * interface
-*   subroutine get_maxrss() result(maxrss) bind(c)
+*   subroutine get_maxrss(maxrss_bytes) bind(c)
 *       use iso_c_binding, only : c_long
-*       integer (c_long), intent(out) :: maxrss
+*       integer (c_long), intent(out) :: maxrss_bytes
 *   end subroutine get_maxrss
 * end interface
 */
 void get_maxrss(long *maxrss_bytes) {
 
-    int conversion;
+    long conversion;
     struct rusage usage;
 
-#if  defined(__APPLE_) || defined(__MACH__)
-    // BSD's ru_maxrss (used by Apple) is in bytes
-    conversion = 1.0;
-#elif __linux__
-    // Linux's ru_maxrss is in KiB
-    conversion = 1000.0;
+#if defined(__APPLE__) && defined(__MACH__)
+    // On macOS, ru_maxrss is already in bytes.
+    conversion = 1L;
+#elif defined(__linux__)
+    // On Linux, ru_maxrss is reported in KiB.
+    conversion = 1024L;
 #else
-    conversion = 1.0;
+    // Other BSDs (FreeBSD, OpenBSD, NetBSD) also report KiB.
+    conversion = 1024L;
 #endif
 
     getrusage(RUSAGE_SELF, &usage);
-    *maxrss_bytes = usage.ru_maxrss / conversion;
+    *maxrss_bytes = usage.ru_maxrss * conversion;
 }
diff --git a/f90/UTILS/ModEM_memory.f90 b/f90/UTILS/ModEM_memory.f90
index 158cbdb1..c1dec646 100644
--- a/f90/UTILS/ModEM_memory.f90
+++ b/f90/UTILS/ModEM_memory.f90
@@ -15,6 +15,7 @@ module ModEM_memory
 
     use utilities
     use iso_c_binding, only : c_long
+    use iso_fortran_env, only : int64, real64
 #ifdef MPI
     use mpi
 #endif
@@ -24,8 +25,6 @@ module ModEM_memory
 
     private
 
-    integer :: task_id
-
     public ModEM_memory_print_report
     public ModEM_memory_log_report
 #ifdef MPI
@@ -38,7 +37,7 @@ subroutine ModEM_memory_get_maxrss(maxrss_bytes)
 
         implicit none
 
-        integer, intent(out) :: maxrss_bytes
+        integer (int64), intent(out) :: maxrss_bytes
         integer (c_long) :: maxrss_bytes_c
 
 #ifdef MODEM_MEMORY
@@ -50,7 +49,7 @@ end subroutine get_maxrss
         end interface
 
         call get_maxrss(maxrss_bytes_c)
-        maxrss_bytes = maxrss_bytes_c
+        maxrss_bytes = int(maxrss_bytes_c, int64)
 #else
         write(0,*) "ERROR: ModEM was not built with the ModEM_getrusage.c file!"
         write(0,*) "ERROR: In order to use ModEM_memory routines you must"
@@ -64,16 +63,16 @@ subroutine ModEM_memory_print_report(message)
 
         implicit none
 
-        integer :: maxrss
+        integer (int64) :: maxrss
         character (len=*), intent(in) :: message
-        real :: maxrss_bytes, maxrss_kb, maxrss_mb, maxrss_gb
-        character (len=*), parameter :: LOG_MSG_FMT = "(I4.4, A, A, A, F18.1, A, F18.1, A, F18.1, A)"
+        real (real64) :: maxrss_kb, maxrss_mb, maxrss_gb
+        character (len=*), parameter :: LOG_MSG_FMT = "(A, A, F18.1, A, F18.1, A, F18.1, A)"
         character (len=512) :: log_message
 
         call ModEM_memory_get_maxrss(maxrss)
         call ModEM_memory_convert_maxrss(maxrss, maxrss_kb, maxrss_mb, maxrss_gb)
 
-        write(log_message, LOG_MSG_FMT) task_id, ' - ', trim(message), ", ", maxrss_kb, ' kb ', maxrss_mb, ' mb ', maxrss_gb, ' gb'
+        write(log_message, LOG_MSG_FMT) trim(message), ", ", maxrss_kb, ' kb ', maxrss_mb, ' mb ', maxrss_gb, ' gb'
         write(6,*) trim(log_message)
 
     end subroutine ModEM_memory_print_report
@@ -82,14 +81,14 @@ subroutine ModEM_memory_convert_maxrss(maxrss_bytes, maxrss_kb, maxrss_mb, maxrs
 
         implicit none
 
-        integer :: maxrss_bytes
-        real, intent(out) :: maxrss_kb
-        real, intent(out) :: maxrss_mb
-        real, intent(out) :: maxrss_gb
+        integer (int64), intent(in) :: maxrss_bytes
+        real (real64), intent(out) :: maxrss_kb
+        real (real64), intent(out) :: maxrss_mb
+        real (real64), intent(out) :: maxrss_gb
 
-        maxrss_kb = maxrss_bytes / 1.0
-        maxrss_mb = maxrss_kb / 1000.0
-        maxrss_gb = maxrss_mb / 1000.1
+        maxrss_kb = real(maxrss_bytes, real64) / 1024.0_real64
+        maxrss_mb = maxrss_kb / 1024.0_real64
+        maxrss_gb = maxrss_mb / 1024.0_real64
 
     end subroutine ModEM_memory_convert_maxrss
 
@@ -99,8 +98,8 @@ subroutine ModEM_memory_log_report(message)
 
         character (len=*), intent(in) :: message
         character (len=*), parameter :: LOG_MSG_FMT = "(A, A, F18.1, A, F18.1, A, F18.1, A)"
-        integer :: maxrss
-        real :: maxrss_kb, maxrss_mb, maxrss_gb
+        integer (int64) :: maxrss
+        real (real64) :: maxrss_kb, maxrss_mb, maxrss_gb
         character (len=512) :: log_message
 
         call ModEM_memory_get_maxrss(maxrss)
@@ -120,12 +119,12 @@ subroutine ModEM_memory_get_all(message)
         character (len=*), parameter :: LOG_MSG_FMT = "(A, A, F18.1, A, F18.1, A, F18.1, A)"
         character (len=512) :: log_message
 
-        integer :: maxrss, global_maxrss
-        real :: maxrss_kb, maxrss_mb, maxrss_gb
+        integer (int64) :: maxrss, global_maxrss
+        real (real64) :: maxrss_kb, maxrss_mb, maxrss_gb
 
         call ModEM_memory_get_maxrss(maxrss)
 
-        call MPI_reduce(maxrss, global_maxrss, 1, MPI_INTEGER, MPI_SUM, 0, MPI_COMM_WORLD, ierr)
+        call MPI_reduce(maxrss, global_maxrss, 1, MPI_INTEGER8, MPI_SUM, 0, MPI_COMM_WORLD, ierr)
 
         if (taskid == 0) then
             call ModEM_memory_convert_maxrss(global_maxrss, maxrss_kb, maxrss_mb, maxrss_gb)