diff --git a/libraries/chain/wasm_interface.cpp b/libraries/chain/wasm_interface.cpp
index 28de213c1c2..c8f81cacca3 100644
--- a/libraries/chain/wasm_interface.cpp
+++ b/libraries/chain/wasm_interface.cpp
@@ -22,6 +22,7 @@
 #include <boost/asio.hpp>
 #include <boost/bind.hpp>
 #include <fstream>
+#include <string.h>
 
 namespace eosio { namespace chain {
    using namespace webassembly;
@@ -901,6 +902,8 @@ class system_api : public context_aware_api {
 
 };
 
+constexpr size_t max_assert_message = 1024;
+
 class context_free_system_api :  public context_aware_api {
 public:
    explicit context_free_system_api( apply_context& ctx )
@@ -913,14 +916,16 @@ class context_free_system_api :  public context_aware_api {
    // Kept as intrinsic rather than implementing on WASM side (using eosio_assert_message and strlen) because strlen is faster on native side.
    void eosio_assert( bool condition, null_terminated_ptr msg ) {
       if( BOOST_UNLIKELY( !condition ) ) {
-         std::string message( msg );
+         const size_t sz = strnlen( msg, max_assert_message );
+         std::string message( msg, sz );
          EOS_THROW( eosio_assert_message_exception, "assertion failure with message: ${s}", ("s",message) );
       }
    }
 
    void eosio_assert_message( bool condition, array_ptr<const char> msg, size_t msg_len ) {
       if( BOOST_UNLIKELY( !condition ) ) {
-         std::string message( msg, msg_len );
+         const size_t sz = msg_len > max_assert_message ? max_assert_message : msg_len;
+         std::string message( msg, sz );
          EOS_THROW( eosio_assert_message_exception, "assertion failure with message: ${s}", ("s",message) );
       }
    }