diff --git a/src/engine/engine_plugin.cc b/src/engine/engine_plugin.cc
index ec0a1ef50a..850d4269db 100644
--- a/src/engine/engine_plugin.cc
+++ b/src/engine/engine_plugin.cc
@@ -194,7 +194,7 @@ bool GlobalTable<mjpPlugin>::CopyObject(mjpPlugin& dst, const mjpPlugin& src, Er
 
   // check and copy plugin attributes
   std::unique_ptr<std::unique_ptr<char[]>[]> attributes_list;
-  if (src.nattribute) {
+  if (src.nattribute && src.nattribute <= kMaxAttributes) {
     attributes_list.reset(new(std::nothrow) std::unique_ptr<char[]>[src.nattribute]);
     if (!attributes_list) {
       std::snprintf(err, sizeof(err), "failed to allocate memory for plugin attribute list");
diff --git a/src/engine/engine_print.c b/src/engine/engine_print.c
index a8f407d934..57d11962e7 100644
--- a/src/engine/engine_print.c
+++ b/src/engine/engine_print.c
@@ -480,7 +480,7 @@ static bool validateFloatFormat(const char* float_format) {
   // flag characters. allow at most one of each flag
   const char flag_characters[] = "-+ #0";
   int flag_character_counts[sizeof(flag_characters)] = { 0 };
-  char* c;
+  const char* c;
   while (c = strchr(flag_characters, float_format[cur_idx]), c != NULL) {
     int flag_idx = (c - flag_characters)/sizeof(char);
     flag_character_counts[flag_idx]++;