diff --git a/digressions/temperatures.c b/digressions/temperatures.c
index 1e6f375..9400b0e 100644
--- a/digressions/temperatures.c
+++ b/digressions/temperatures.c
@@ -1,6 +1,5 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 
 
 double c2f(double celsius) {
@@ -14,7 +13,7 @@ double f2c(double fahrenheit) {
 
 
 int die_usage(const char *msg) {
-    printf("Usage: temperatures [FC]<temp>\n");
+    printf("Usage: temperatures <temp>[fFcC]\n");
     printf("%s\n", msg);
     exit(1);
 }
@@ -27,20 +26,23 @@ int main(int argc, char * argv[]) {
 
     char msg[255];
     double temp;
+    char scale = '\0';
     const char * temp_string = argv[1];
 
-    size_t temp_len = strlen(temp_string);
-
-    if (strncmp(temp_string, "F", temp_len) > -1) {
-        sscanf(temp_string, "F%lf", &temp);
-        printf("%.2lf\n", f2c(temp));
-    } else if (strncmp(temp_string, "C", temp_len) > -1) {
-        sscanf(temp_string, "C%lf", &temp);
-        printf("%.2lf\n", c2f(temp));
-    } else {
-        sprintf(msg, "Argument '%s' does not match '[FC]<temp>'",
-                temp_string);
-        die_usage(msg);
+    sscanf(temp_string, "%lf%c", &temp, &scale);
+    switch (scale) {
+        case 'c':
+        case 'C':
+            printf("%.2lf\n", c2f(temp));
+            break;
+        case 'f':
+        case 'F':
+            printf("%.2lf\n", f2c(temp));
+            break;
+        default:
+            sprintf(msg, "Unknown scale '%c'", scale);
+            die_usage(msg);
+            break;
     }
 
     return 0;