diff --git a/library/sha512.c b/library/sha512.c
index 5ed920b..a91d792 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -844,7 +844,7 @@
         memset(ctx->buffer + used, 0, SHA512_BLOCK_SIZE - used);
 
         if ((ret = mbedtls_internal_sha512_process(ctx, ctx->buffer)) != 0) {
-            return ret;
+            goto exit;
         }
 
         memset(ctx->buffer, 0, 112);
@@ -861,7 +861,7 @@
     sha512_put_uint64_be(low,  ctx->buffer, 120);
 
     if ((ret = mbedtls_internal_sha512_process(ctx, ctx->buffer)) != 0) {
-        return ret;
+        goto exit;
     }
 
     /*
@@ -883,7 +883,11 @@
         sha512_put_uint64_be(ctx->state[7], output, 56);
     }
 
-    return 0;
+    ret = 0;
+
+exit:
+    mbedtls_sha512_free(ctx);
+    return ret;
 }
 
 #endif /* !MBEDTLS_SHA512_ALT */