diff --git a/tests/prng.h b/tests/prng.h
index ed36498..cf0bacc 100644
--- a/tests/prng.h
+++ b/tests/prng.h
@@ -29,6 +29,10 @@
 
 struct prng* prng_new(unsigned long long seed);
 unsigned int prng_rand(struct prng*);
+const char * prng_fuzz(struct prng*,
+                       const char *string,
+                       const char *charset,
+                       unsigned int operations);
 void prng_free(struct prng *);
 
 #endif