diff --git a/test/default/secretbox_easy.c b/test/default/secretbox_easy.c
index df85070a..5a063af4 100644
--- a/test/default/secretbox_easy.c
+++ b/test/default/secretbox_easy.c
@@ -24,7 +24,7 @@ unsigned char m[131]
         0x60, 0x90, 0x2e, 0x52, 0xf0, 0xa0, 0x89, 0xbc, 0x76, 0x89, 0x70, 0x40,
         0xe0, 0x82, 0xf9, 0x37, 0x76, 0x38, 0x48, 0x64, 0x5e, 0x07, 0x05 };
 
-unsigned char c[147 + crypto_secretbox_MACBYTES];
+unsigned char c[147 + crypto_secretbox_MACBYTES + 1];
 unsigned char mac[crypto_secretbox_MACBYTES];
 
 int main(void)
@@ -50,6 +50,36 @@ int main(void)
         if (i % 8 == 7)
             printf("\n");
     }
+    printf("\n");
+
+    /* Same test, with c and m overlapping */
+
+    memcpy(c + 1, m, 131);
+    crypto_secretbox_easy(c, c + 1, 131, nonce, firstkey);
+    for (i = 0; i < 131 + crypto_secretbox_MACBYTES; ++i) {
+        printf(",0x%02x", (unsigned int)c[i]);
+        if (i % 8 == 7)
+            printf("\n");
+    }
+    printf("\n");
+
+    memcpy(c, m, 131);
+    crypto_secretbox_easy(c + 1, c, 131, nonce, firstkey);
+    for (i = 0; i < 131 + crypto_secretbox_MACBYTES; ++i) {
+        printf(",0x%02x", (unsigned int)c[i + 1]);
+        if (i % 8 == 7)
+            printf("\n");
+    }
+    printf("\n");
+
+    memcpy(c, m, 131);
+    crypto_secretbox_easy(c, c, 131, nonce, firstkey);
+    for (i = 0; i < 131 + crypto_secretbox_MACBYTES; ++i) {
+        printf(",0x%02x", (unsigned int)c[i]);
+        if (i % 8 == 7)
+            printf("\n");
+    }
+    printf("\n");
 
     assert(crypto_secretbox_easy(c, m, SIZE_MAX - 1U, nonce, firstkey) == -1);
 
diff --git a/test/default/secretbox_easy.exp b/test/default/secretbox_easy.exp
index c4b4066b..2c9741e9 100644
--- a/test/default/secretbox_easy.exp
+++ b/test/default/secretbox_easy.exp
@@ -35,4 +35,61 @@
 ,0x56,0x24,0x4a,0x9e,0x88,0xd5,0xf9,0xb3
 ,0x79,0x73,0xf6,0x22,0xa4,0x3d,0x14,0xa6
 ,0x59,0x9b,0x1f,0x65,0x4c,0xb4,0x5a,0x74
-,0xe3,0x55,0xa5
\ No newline at end of file
+,0xe3,0x55,0xa5
+,0xf3,0xff,0xc7,0x70,0x3f,0x94,0x00,0xe5
+,0x2a,0x7d,0xfb,0x4b,0x3d,0x33,0x05,0xd9
+,0x8e,0x99,0x3b,0x9f,0x48,0x68,0x12,0x73
+,0xc2,0x96,0x50,0xba,0x32,0xfc,0x76,0xce
+,0x48,0x33,0x2e,0xa7,0x16,0x4d,0x96,0xa4
+,0x47,0x6f,0xb8,0xc5,0x31,0xa1,0x18,0x6a
+,0xc0,0xdf,0xc1,0x7c,0x98,0xdc,0xe8,0x7b
+,0x4d,0xa7,0xf0,0x11,0xec,0x48,0xc9,0x72
+,0x71,0xd2,0xc2,0x0f,0x9b,0x92,0x8f,0xe2
+,0x27,0x0d,0x6f,0xb8,0x63,0xd5,0x17,0x38
+,0xb4,0x8e,0xee,0xe3,0x14,0xa7,0xcc,0x8a
+,0xb9,0x32,0x16,0x45,0x48,0xe5,0x26,0xae
+,0x90,0x22,0x43,0x68,0x51,0x7a,0xcf,0xea
+,0xbd,0x6b,0xb3,0x73,0x2b,0xc0,0xe9,0xda
+,0x99,0x83,0x2b,0x61,0xca,0x01,0xb6,0xde
+,0x56,0x24,0x4a,0x9e,0x88,0xd5,0xf9,0xb3
+,0x79,0x73,0xf6,0x22,0xa4,0x3d,0x14,0xa6
+,0x59,0x9b,0x1f,0x65,0x4c,0xb4,0x5a,0x74
+,0xe3,0x55,0xa5
+,0xf3,0xff,0xc7,0x70,0x3f,0x94,0x00,0xe5
+,0x2a,0x7d,0xfb,0x4b,0x3d,0x33,0x05,0xd9
+,0x8e,0x99,0x3b,0x9f,0x48,0x68,0x12,0x73
+,0xc2,0x96,0x50,0xba,0x32,0xfc,0x76,0xce
+,0x48,0x33,0x2e,0xa7,0x16,0x4d,0x96,0xa4
+,0x47,0x6f,0xb8,0xc5,0x31,0xa1,0x18,0x6a
+,0xc0,0xdf,0xc1,0x7c,0x98,0xdc,0xe8,0x7b
+,0x4d,0xa7,0xf0,0x11,0xec,0x48,0xc9,0x72
+,0x71,0xd2,0xc2,0x0f,0x9b,0x92,0x8f,0xe2
+,0x27,0x0d,0x6f,0xb8,0x63,0xd5,0x17,0x38
+,0xb4,0x8e,0xee,0xe3,0x14,0xa7,0xcc,0x8a
+,0xb9,0x32,0x16,0x45,0x48,0xe5,0x26,0xae
+,0x90,0x22,0x43,0x68,0x51,0x7a,0xcf,0xea
+,0xbd,0x6b,0xb3,0x73,0x2b,0xc0,0xe9,0xda
+,0x99,0x83,0x2b,0x61,0xca,0x01,0xb6,0xde
+,0x56,0x24,0x4a,0x9e,0x88,0xd5,0xf9,0xb3
+,0x79,0x73,0xf6,0x22,0xa4,0x3d,0x14,0xa6
+,0x59,0x9b,0x1f,0x65,0x4c,0xb4,0x5a,0x74
+,0xe3,0x55,0xa5
+,0xf3,0xff,0xc7,0x70,0x3f,0x94,0x00,0xe5
+,0x2a,0x7d,0xfb,0x4b,0x3d,0x33,0x05,0xd9
+,0x8e,0x99,0x3b,0x9f,0x48,0x68,0x12,0x73
+,0xc2,0x96,0x50,0xba,0x32,0xfc,0x76,0xce
+,0x48,0x33,0x2e,0xa7,0x16,0x4d,0x96,0xa4
+,0x47,0x6f,0xb8,0xc5,0x31,0xa1,0x18,0x6a
+,0xc0,0xdf,0xc1,0x7c,0x98,0xdc,0xe8,0x7b
+,0x4d,0xa7,0xf0,0x11,0xec,0x48,0xc9,0x72
+,0x71,0xd2,0xc2,0x0f,0x9b,0x92,0x8f,0xe2
+,0x27,0x0d,0x6f,0xb8,0x63,0xd5,0x17,0x38
+,0xb4,0x8e,0xee,0xe3,0x14,0xa7,0xcc,0x8a
+,0xb9,0x32,0x16,0x45,0x48,0xe5,0x26,0xae
+,0x90,0x22,0x43,0x68,0x51,0x7a,0xcf,0xea
+,0xbd,0x6b,0xb3,0x73,0x2b,0xc0,0xe9,0xda
+,0x99,0x83,0x2b,0x61,0xca,0x01,0xb6,0xde
+,0x56,0x24,0x4a,0x9e,0x88,0xd5,0xf9,0xb3
+,0x79,0x73,0xf6,0x22,0xa4,0x3d,0x14,0xa6
+,0x59,0x9b,0x1f,0x65,0x4c,0xb4,0x5a,0x74
+,0xe3,0x55,0xa5