diff --git a/guest/src/crc32c.cpp b/guest/src/crc32c.cpp
index 2515f498..edf02582 100644
--- a/guest/src/crc32c.cpp
+++ b/guest/src/crc32c.cpp
@@ -1,5 +1,8 @@
 #include "api.hpp"
 
+#include <stdlib.h>
+extern "C" void* malloc(size_t);
+extern "C" void free(void*);
 #include <immintrin.h>
 
 inline bool ____is__aligned(const void* buffer, const int align) noexcept {
diff --git a/guest/src/guest.cpp b/guest/src/guest.cpp
index a6331fb7..11316988 100644
--- a/guest/src/guest.cpp
+++ b/guest/src/guest.cpp
@@ -32,6 +32,9 @@ struct Data {
 	size_t len;
 };
 
+#include <stdlib.h>
+extern "C" void* malloc(size_t);
+extern "C" void free(void*);
 #include <immintrin.h>
 PUBLIC(uint32_t empty(const Data& data))
 {