diff --git a/src/main.c b/src/main.c
index 1ccc1d1a..5d239ab2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,9 +1,11 @@
 #include <stdio.h>
 
+#define LINE_MAX_LENGTH 256
+
 int
 main()
 {
-  char line[256], last_char;
+  char line[LINE_MAX_LENGTH], last_char;
   int char_index;
 
   while (1) {
@@ -13,6 +15,8 @@ main()
     while ((last_char = getchar()) != '\n') {
       if (last_char == EOF)
 	goto eof;
+      if (char_index == LINE_MAX_LENGTH)
+	goto overflow;
       line[char_index++] = last_char;
     }
     line[char_index] = '\0';
@@ -25,6 +29,12 @@ main()
 
  eof:
   puts("");
+  goto exit;
 
+ overflow:
+  puts("** [fatal] line input overflow");
+  goto exit;
+
+ exit:
   return 0;
 }