diff --git a/main.c b/main.c
index 8eb557c..6157d49 100644
--- a/main.c
+++ b/main.c
@@ -144,6 +144,11 @@ int get_temp() {
     int value = 0;
     size_t len = sizeof(sensor);
 
+    if (!temperature_sensor_found) {
+        errno = ENOENT;
+        err(1, "no temperature sensor");
+    }
+
     if (sysctl(temperature_mib, 5, &sensor, &len, NULL, 0) == -1)
         err(1, "failed to read temperature");
 
@@ -202,9 +207,15 @@ void switch_batt() {
 /* assign values to variable if comma separated
  * if not, assign value to two variables
  */
-void assign_values_from_param(char* parameter, int* charging, int* battery) {
+void assign_values_from_param(char* parameterk, int* charging, int* battery) {
+    char *parameter = strdup(parameterk);
     int count = 0;
-    char *token = strtok(parameter, ",");
+    char *token = NULL;
+
+    if(parameter == NULL)
+        err(1, "malloc failed");
+
+    token = strtok(parameter, ",");
 
     while (token != NULL) {
         if(count == 0)
@@ -224,6 +235,8 @@ void assign_values_from_param(char* parameter, int* charging, int* battery) {
 
     if(count == 1)
         *battery = *charging;
+
+    free(parameter);
 }
 
 /* parse optarg for a sensor path, sysctl style;
@@ -232,7 +245,7 @@ void assign_values_from_param(char* parameter, int* charging, int* battery) {
  * IFF it's a valid path, else sets errno to something
  * relevant.
  */
-void parse_sensor_path(char* path) {
+void parse_sensor_path(char* pathk) {
     const struct ctlnameconst ctlnames[] = CTL_NAMES;
     const struct ctlnameconst ctlhwnames[] = CTL_HW_NAMES;
     const size_t prefix_len = 
@@ -240,7 +253,8 @@ void parse_sensor_path(char* path) {
         /*.*/1 +
         /*sensors*/strlen(ctlhwnames[HW_SENSORS].ctl_name) +
         /*.*/1;
-    char* prefix = malloc(prefix_len + 1);
+    char* path = NULL;
+    char* prefix = NULL;
     /* these are pointers into optarg */
     char* sensordevname = NULL, *sensortype = NULL, *sensornumts = NULL;
     int sensornumt = -1;
@@ -248,10 +262,14 @@ void parse_sensor_path(char* path) {
     const char* errstr = NULL;
     int dev = 0;
 
-    if(prefix == NULL) {
-        errno = ENOMEM;
-        return;
-    }
+    path = strdup(pathk);
+    if(path == NULL)
+        err(1, "malloc failed");
+
+    prefix = malloc(prefix_len + 1);
+    if(prefix == NULL)
+        err(1, "malloc failed");
+
     memset(prefix, 0, prefix_len + 1);
     strcpy(prefix, ctlnames[CTL_HW].ctl_name);
     strcat(prefix, ".");
@@ -300,7 +318,7 @@ void parse_sensor_path(char* path) {
         if(verbose)
             fprintf(stderr,
                     "%s does not look like a temperature sensor\n",
-                    path);
+                    pathk);
         errno = EINVAL;
         goto badprefix;
     }
@@ -364,6 +382,7 @@ void parse_sensor_path(char* path) {
 
 badprefix:
     free(prefix);
+    free(path);
 }
 
 
@@ -421,12 +440,14 @@ int main(int argc, char *argv[]) {
             break;
         case 'l':
             assign_values_from_param(optarg, &wall_min, &batt_min);
-            if(hard_min_freq > 100 || hard_min_freq < 0)
+            if(wall_min > 100 || wall_min < 0 ||
+                    batt_min > 100 || batt_min < 0)
                 err(1, "minimum frequency must be between 0 and 100");
             break;
         case 'm':
             assign_values_from_param(optarg, &wall_max, &batt_max);
-            if(hard_max_freq > 100 || hard_max_freq < 0)
+            if(wall_max > 100 || wall_max < 0 ||
+                    batt_max > 100 || batt_max < 0)
                 err(1, "maximum frequency must be between 0 and 100");
             break;
         case 'v':