diff --git a/test/default/auth.c b/test/default/auth.c
index 5da0d0e3..88c8207f 100644
--- a/test/default/auth.c
+++ b/test/default/auth.c
@@ -5,14 +5,14 @@
 
 /* "Test Case 2" from RFC 4231 */
 unsigned char key[32] = "Jefe";
-unsigned char c[28] = "what do ya want for nothing?";
+unsigned char c[] = "what do ya want for nothing?";
 
 unsigned char a[32];
 
 int main(void)
 {
   int i;
-  crypto_auth_hmacsha512256(a,c,sizeof c,key);
+  crypto_auth_hmacsha512256(a,c,sizeof c - 1U,key);
   for (i = 0;i < 32;++i) {
     printf(",0x%02x",(unsigned int) a[i]);
     if (i % 8 == 7) printf("\n");
diff --git a/test/default/hash.c b/test/default/hash.c
index fa0c29a8..47950fc7 100644
--- a/test/default/hash.c
+++ b/test/default/hash.c
@@ -3,13 +3,13 @@
 #define TEST_NAME "hash"
 #include "cmptest.h"
 
-unsigned char x[8] = "testing\n";
+unsigned char x[] = "testing\n";
 unsigned char h[crypto_hash_BYTES];
 
 int main(void)
 {
   int i;
-  crypto_hash(h,x,sizeof x);
+  crypto_hash(h,x,sizeof x - 1U);
   for (i = 0;i < crypto_hash_BYTES;++i) printf("%02x",(unsigned int) h[i]);
   printf("\n");
   return 0;
diff --git a/test/default/hash3.c b/test/default/hash3.c
index e56660b7..2fae6200 100644
--- a/test/default/hash3.c
+++ b/test/default/hash3.c
@@ -3,13 +3,13 @@
 #define TEST_NAME "hash3"
 #include "cmptest.h"
 
-unsigned char x[8] = "testing\n";
+unsigned char x[] = "testing\n";
 unsigned char h[crypto_hash_sha512_BYTES];
 
 int main(void)
 {
   int i;
-  crypto_hash_sha512(h,x,sizeof x);
+  crypto_hash_sha512(h,x,sizeof x - 1U);
   for (i = 0;i < crypto_hash_sha512_BYTES;++i) printf("%02x",(unsigned int) h[i]);
   printf("\n");
   return 0;