diff --git a/src/macos.c b/src/macos.c
index 9a79ed6..57cd48e 100644
--- a/src/macos.c
+++ b/src/macos.c
@@ -2,13 +2,15 @@
 #include <time.h>
 #include <mach/mach_time.h>
 #include <stdlib.h>
-#include <math.h>
 
 #include "lfmacos.h"
 
+#define NS_TO_SECONDS 1000000000.0
+#define NEW_PROCESS_SENTINEL (-1.0)
+
 ProcessData *new_ProcessData() {
     ProcessData *pd = malloc(sizeof(ProcessData));
-    pd->last_total_consumed = -1.0;
+    pd->last_total_consumed = NEW_PROCESS_SENTINEL;
     return pd;
 }
 
@@ -24,18 +26,18 @@ int update_process(pid_t pid, ProcessData *proc) {
     const double ns_per_tick = (double)info.numer / (double)info.denom;
 
     time(&(proc->timestamp));
-    proc->total_kernel_time = (taskinfo.pti_total_system * ns_per_tick) / 1000000000.0;
-    proc->total_user_time = (taskinfo.pti_total_user * ns_per_tick) / 1000000000.0;
+    proc->total_kernel_time = (taskinfo.pti_total_system * ns_per_tick) / NS_TO_SECONDS;
+    proc->total_user_time = (taskinfo.pti_total_user * ns_per_tick) / NS_TO_SECONDS;
     proc->virtual_memory = taskinfo.pti_virtual_size;
     proc->resident_memory = taskinfo.pti_resident_size;
 
-    if (proc->last_total_consumed > -1.0) {
-        proc->percent_cpu = fabs(100.0 *
-        (proc->total_user_time + proc->total_kernel_time - proc->last_total_consumed) /
-        (proc->last_timestamp - proc->timestamp));
+    if (proc->last_total_consumed != NEW_PROCESS_SENTINEL) {
+        time_t t = proc->timestamp - proc->last_timestamp;
+        proc->percent_cpu = 100.0 * (proc->total_user_time + proc->total_kernel_time - proc->last_total_consumed) / t;
     } else {
         proc->percent_cpu = 0.0;
     }
+
     proc->last_timestamp = proc->timestamp;
     proc->last_total_consumed = proc->total_kernel_time + proc->total_user_time;
 
diff --git a/tests/tests.c b/tests/tests.c
index 60d8c7e..04c2b95 100644
--- a/tests/tests.c
+++ b/tests/tests.c
@@ -179,6 +179,10 @@ void test_math() {
     printf("Binary: %s\n", s2);
     printf("Decimal: %d\n", binstr_to_int(s2));
 
+    i = 10;
+    i = clamp_int(i, 2, 5);
+    assert(i == 5);
+
     printf("\nGenerate line from 0,0 to 2,5\n");
     size_t sz = 0;
     Point *line = bresenham(0, 0, 2, 5, &sz);