diff --git a/muri.c b/muri.c
index 1ec9e51..4992bf8 100644
--- a/muri.c
+++ b/muri.c
@@ -7,30 +7,49 @@
 
 int
 main(int argc, char *argv[]) {
+    int encode = 1;
+    int read_stdin = 1;
     int maximum_read = 10*1024*1024;
+
+    char *usage = "Usage: muri [-h] [-d]\n    reads from stdin, encode is default, -d to decode\n";
+
+    if (argc > 1) {
+        for (int i = 1; i < argc; ++i) {
+            if (strncmp(argv[i], "-h", 2) == 0) {
+                fprintf(stderr, usage);
+                return 1;
+            } else if (strncmp(argv[i], "-d", 2) == 0) {
+                encode = 0;
+            }
+        }
+    }
+
     char *input_buffer = malloc(sizeof(char)*maximum_read);
     assert( input_buffer != NULL );
-    if (argc < 2) {
-        if (fgets(input_buffer, maximum_read, stdin) == NULL) {
-            return 1;
-        }
-        // Throw away the newline.
-        if (input_buffer[strnlen(input_buffer, maximum_read)-1] == '\n') {
-            input_buffer[strnlen(input_buffer, maximum_read)-1] = '\0';
-        } // FIXME if not then we didn't read all of stdin
+    
+    // Read from stdin.
+    if (fgets(input_buffer, maximum_read, stdin) == NULL) {
+        return 1;
+    }
+    // Throw away the newline.
+    if (input_buffer[strnlen(input_buffer, maximum_read)-1] == '\n') {
+        input_buffer[strnlen(input_buffer, maximum_read)-1] = '\0';
     } else {
-        if (strncmp(argv[1], "-h", 2) == 0) {
-            fprintf(stderr, "Usage: %s [string]\nIf [string] not provided, reads from stdin.\n", argv[0]);
-            return 1;
-        } else {
-            // string is on the command-line
-            strncpy(input_buffer, argv[1], maximum_read);
-        }
+        fprintf(stderr, "ERROR: Input too large.\n");
+        // FIXME: realloc or allow configurable buffer size
+        return 1;
     }
 
     int return_value = 0;
     int output_length = 0;
-    char *output = uriencode(input_buffer, &output_length);
+    char *output = NULL;
+
+    if (encode) {
+        output = uriencode(input_buffer, &output_length);
+    } else {
+        output = uridecode(input_buffer, &output_length);
+    }
+
     if (output != NULL) {
         printf("%s\n", output);
     } else {