1 files changed, 3 insertions, 0 deletions
diff --git a/src/glsl/apps/purify.c b/src/glsl/apps/purify.c
index 8c01f4fc6a3..5ab6bae96d1 100644
--- a/src/glsl/apps/purify.c
+++ b/src/glsl/apps/purify.c
@@ -25,6 +25,7 @@
  * 
  **************************************************************************/
 
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -45,6 +46,7 @@ main(int argc,
    FILE *out;
 
    if (argc != 3) {
+      printf("Usage: purify infile outfile\n");
       return 1;
    }
 
@@ -55,6 +57,7 @@ main(int argc,
 
    fseek(in, 0, SEEK_END);
    size = ftell(in);
+   assert(size != -1);
    fseek(in, 0, SEEK_SET);
 
    out = fopen(argv[2], "wb");