diff --git a/src/blake2b-ref.c b/src/blake2b-ref.c
index b153bcb..4d40764 100644
--- a/src/blake2b-ref.c
+++ b/src/blake2b-ref.c
@@ -340,7 +340,7 @@ int blake2b_final( blake2b_state *S, uint8_t *out, size_t outlen )
     blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
     blake2b_compress( S, S->buf );
     S->buflen -= BLAKE2B_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
   }
 
   blake2b_increment_counter( S, S->buflen );
diff --git a/src/blake2b.c b/src/blake2b.c
index c1b8e90..6ac57f2 100644
--- a/src/blake2b.c
+++ b/src/blake2b.c
@@ -395,7 +395,7 @@ int blake2b_final( blake2b_state *S, uint8_t *out, size_t outlen )
     blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
     blake2b_compress( S, S->buf );
     S->buflen -= BLAKE2B_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
   }
 
   blake2b_increment_counter( S, S->buflen );
diff --git a/src/blake2s-ref.c b/src/blake2s-ref.c
index 38bfdbe..db7390f 100644
--- a/src/blake2s-ref.c
+++ b/src/blake2s-ref.c
@@ -330,7 +330,7 @@ int blake2s_final( blake2s_state *S, uint8_t *out, size_t outlen )
     blake2s_increment_counter( S, BLAKE2S_BLOCKBYTES );
     blake2s_compress( S, S->buf );
     S->buflen -= BLAKE2S_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
   }
 
   blake2s_increment_counter( S, ( uint32_t )S->buflen );
diff --git a/src/blake2s.c b/src/blake2s.c
index a05b8af..db97974 100644
--- a/src/blake2s.c
+++ b/src/blake2s.c
@@ -370,7 +370,7 @@ int blake2s_final( blake2s_state *S, uint8_t *out, size_t outlen )
     blake2s_increment_counter( S, BLAKE2S_BLOCKBYTES );
     blake2s_compress( S, S->buf );
     S->buflen -= BLAKE2S_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
   }
 
   blake2s_increment_counter( S, ( uint32_t )S->buflen );