diff --git a/src/hooks.c b/src/hooks.c
index f67e177..6c0f399 100644
--- a/src/hooks.c
+++ b/src/hooks.c
@@ -14,6 +14,7 @@
  */
 
 #include <stdlib.h>
+#include <assert.h>
 #include <cjson/cJSON.h>
 #include <mastodont_hooks.h>
 
@@ -26,12 +27,20 @@ struct mstdnt_hooks _mstdnt_hooks_def = {
 
 void mstdnt_set_hooks(struct mstdnt_hooks* hooks)
 {
+    assert(hooks != NULL);
     cJSON_Hooks cjson_hooks = {
         .malloc_fn = hooks->malloc,
         .free_fn = hooks->free,
     };
     cJSON_InitHooks(&cjson_hooks);
 
-    _mstdnt_hooks_def = *hooks;
+    if (hooks->malloc)
+        _mstdnt_hooks_def.malloc = hooks->malloc;
+    if (hooks->free)
+        _mstdnt_hooks_def.free = hooks->free;
+    if (hooks->calloc)
+        _mstdnt_hooks_def.calloc = hooks->calloc;
+    if (hooks->realloc)
+        _mstdnt_hooks_def.realloc = hooks->realloc;
 }