diff --git a/src/Debug.cc b/src/Debug.cc
index 3d2fd26273..4f136f5293 100644
--- a/src/Debug.cc
+++ b/src/Debug.cc
@@ -157,7 +157,8 @@ int TraceState::LogTrace(const char* fmt, ...) {
     }
 
     if ( ! loc.filename ) {
-        loc.filename = util::copy_string("<no filename>");
+        static constexpr const char str[] = "<no filename>";
+        loc.filename = util::copy_string(str, std::size(str) - 1);
         loc.last_line = 0;
     }
 
@@ -675,7 +676,8 @@ string get_context_description(const Stmt* stmt, const Frame* frame) {
     if ( stmt )
         loc = *stmt->GetLocationInfo();
     else {
-        loc.filename = util::copy_string("<no filename>");
+        static constexpr const char str[] = "<no filename>";
+        loc.filename = util::copy_string(str, std::size(str) - 1);
         loc.last_line = 0;
     }
 
diff --git a/src/Expr.cc b/src/Expr.cc
index 80f48dd17c..82ef6d3217 100644
--- a/src/Expr.cc
+++ b/src/Expr.cc
@@ -3362,7 +3362,7 @@ bool FieldAssignExpr::PromoteTo(TypePtr t) {
 bool FieldAssignExpr::IsRecordElement(TypeDecl* td) const {
     if ( td ) {
         td->type = op->GetType();
-        td->id = util::copy_string(field_name.c_str());
+        td->id = util::copy_string(field_name.c_str(), field_name.size());
     }
 
     return true;
diff --git a/src/Stmt.cc b/src/Stmt.cc
index 5bab9618f8..e2ff8567e3 100644
--- a/src/Stmt.cc
+++ b/src/Stmt.cc
@@ -1752,7 +1752,7 @@ WhenInfo::WhenInfo(ExprPtr arg_cond, FuncType::CaptureList* arg_cl, bool arg_is_
 
     auto param_list = new type_decl_list();
     auto count_t = base_type(TYPE_COUNT);
-    param_list->push_back(new TypeDecl(util::copy_string(lambda_param_id.c_str()), count_t));
+    param_list->push_back(new TypeDecl(util::copy_string(lambda_param_id.c_str(), lambda_param_id.size()), count_t));
     auto params = make_intrusive<RecordType>(param_list);
 
     lambda_ft = make_intrusive<FuncType>(params, base_type(TYPE_ANY), FUNC_FLAVOR_FUNCTION);
diff --git a/src/Val.cc b/src/Val.cc
index 885c6a8f59..2550d1d5c4 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -752,6 +752,8 @@ const u_char* StringVal::Bytes() const { return AsString()->Bytes(); }
 
 const char* StringVal::CheckString() const { return AsString()->CheckString(); }
 
+std::pair<const char*, size_t> StringVal::CheckStringWithSize() const { return AsString()->CheckStringWithSize(); }
+
 string StringVal::ToStdString() const {
     auto* bs = AsString();
     return {(char*)bs->Bytes(), static_cast<size_t>(bs->Len())};
diff --git a/src/Val.h b/src/Val.h
index c8c892091a..9ddeec842f 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -546,6 +546,7 @@ public:
     int Len() const;
     const u_char* Bytes() const;
     const char* CheckString() const;
+    std::pair<const char*, size_t> CheckStringWithSize() const;
 
     // Note that one needs to de-allocate the return value of
     // ExpandedString() to avoid a memory leak.
diff --git a/src/ZeekString.cc b/src/ZeekString.cc
index 672149b57e..6d2e39ac31 100644
--- a/src/ZeekString.cc
+++ b/src/ZeekString.cc
@@ -135,10 +135,10 @@ void String::Set(std::string_view str) {
 
 void String::Set(const String& str) { *this = str; }
 
-const char* String::CheckString() const {
+std::pair<const char*, size_t> String::CheckStringWithSize() const {
     void* nulTerm;
     if ( n == 0 )
-        return "";
+        return {"", 0};
 
     nulTerm = memchr(b, '\0', n + final_NUL);
     if ( nulTerm != &b[n] ) {
@@ -151,12 +151,15 @@ const char* String::CheckString() const {
             reporter->Error("string without NUL terminator: \"%s\"", exp_s);
 
         delete[] exp_s;
-        return "<string-with-NUL>";
+        static constexpr const char result[] = "<string-with-NUL>";
+        return {result, std::size(result) - 1};
     }
 
-    return (const char*)b;
+    return {(const char*)b, n};
 }
 
+const char* String::CheckString() const { return CheckStringWithSize().first; }
+
 char* String::Render(int format, int* len) const {
     // Maximum character expansion is as \xHH, so a factor of 4.
     char* s = new char[n * 4 + 1]; // +1 is for final '\0'
diff --git a/src/ZeekString.h b/src/ZeekString.h
index dea4c602e0..44fee2d8cd 100644
--- a/src/ZeekString.h
+++ b/src/ZeekString.h
@@ -84,6 +84,11 @@ public:
      */
     const char* CheckString() const;
 
+    /**
+     * Like @c CheckString(), but also returns the length of the string.
+     */
+    std::pair<const char*, size_t> CheckStringWithSize() const;
+
     enum render_style {
         ESC_NONE = 0,
         ESC_ESC = (1 << 1),  // '\' -> "\\"
diff --git a/src/input/Manager.cc b/src/input/Manager.cc
index 0fd531f00b..2de28b3735 100644
--- a/src/input/Manager.cc
+++ b/src/input/Manager.cc
@@ -215,8 +215,8 @@ bool Manager::CreateStream(Stream* info, RecordVal* description) {
     string source((const char*)bsource->Bytes(), bsource->Len());
 
     ReaderBackend::ReaderInfo rinfo;
-    rinfo.source = util::copy_string(source.c_str());
-    rinfo.name = util::copy_string(name.c_str());
+    rinfo.source = util::copy_string(source.c_str(), source.size());
+    rinfo.name = util::copy_string(name.c_str(), name.size());
 
     auto mode_val = description->GetFieldOrDefault("mode");
     auto mode = mode_val->AsEnumVal();
@@ -244,7 +244,8 @@ bool Manager::CreateStream(Stream* info, RecordVal* description) {
             auto index = info->config->RecreateIndex(*k);
             string key = index->Idx(0)->AsString()->CheckString();
             string value = v->GetVal()->AsString()->CheckString();
-            rinfo.config.insert(std::make_pair(util::copy_string(key.c_str()), util::copy_string(value.c_str())));
+            rinfo.config.insert(std::make_pair(util::copy_string(key.c_str(), key.size()),
+                                               util::copy_string(value.c_str(), value.size())));
         }
     }
 
diff --git a/src/input/readers/ascii/Ascii.cc b/src/input/readers/ascii/Ascii.cc
index a553cd48f0..365336f93d 100644
--- a/src/input/readers/ascii/Ascii.cc
+++ b/src/input/readers/ascii/Ascii.cc
@@ -152,7 +152,7 @@ bool Ascii::OpenFile() {
 
     if ( ! read_location ) {
         read_location = LocationPtr(new zeek::detail::Location());
-        read_location->filename = util::copy_string(fname.c_str());
+        read_location->filename = util::copy_string(fname.c_str(), fname.size());
     }
 
     StopWarningSuppression();
diff --git a/src/input/readers/benchmark/Benchmark.cc b/src/input/readers/benchmark/Benchmark.cc
index 3d79690321..80b6182e1d 100644
--- a/src/input/readers/benchmark/Benchmark.cc
+++ b/src/input/readers/benchmark/Benchmark.cc
@@ -120,7 +120,7 @@ threading::Value* Benchmark::EntryToVal(TypeTag type, TypeTag subtype) {
 
         case TYPE_STRING: {
             std::string rnd = RandomString(10);
-            val->val.string_val.data = util::copy_string(rnd.c_str());
+            val->val.string_val.data = util::copy_string(rnd.c_str(), rnd.size());
             val->val.string_val.length = rnd.size();
             break;
         }
diff --git a/src/input/readers/config/Config.cc b/src/input/readers/config/Config.cc
index 9ad9ddc396..405af70d8d 100644
--- a/src/input/readers/config/Config.cc
+++ b/src/input/readers/config/Config.cc
@@ -222,11 +222,11 @@ bool Config::DoUpdate() {
             Value** fields = new Value*[2];
             Value* keyval = new threading::Value(TYPE_STRING, true);
             keyval->val.string_val.length = key.size();
-            keyval->val.string_val.data = util::copy_string(key.c_str());
+            keyval->val.string_val.data = util::copy_string(key.c_str(), key.size());
             fields[0] = keyval;
             Value* val = new threading::Value(TYPE_STRING, true);
             val->val.string_val.length = value.size();
-            val->val.string_val.data = util::copy_string(value.c_str());
+            val->val.string_val.data = util::copy_string(value.c_str(), value.size());
             fields[1] = val;
 
             if ( Info().mode == MODE_STREAM )
@@ -238,13 +238,15 @@ bool Config::DoUpdate() {
         {
             Value** vals = new Value*[4];
             vals[0] = new Value(TYPE_STRING, true);
-            vals[0]->val.string_val.data = util::copy_string(Info().name);
-            vals[0]->val.string_val.length = strlen(Info().name);
+            auto val0_len = strlen(Info().name);
+            vals[0]->val.string_val.data = util::copy_string(Info().name, val0_len);
+            vals[0]->val.string_val.length = val0_len;
             vals[1] = new Value(TYPE_STRING, true);
-            vals[1]->val.string_val.data = util::copy_string(Info().source);
-            vals[1]->val.string_val.length = strlen(Info().source);
+            auto val1_len = strlen(Info().source);
+            vals[1]->val.string_val.data = util::copy_string(Info().source, val1_len);
+            vals[1]->val.string_val.length = val1_len;
             vals[2] = new Value(TYPE_STRING, true);
-            vals[2]->val.string_val.data = util::copy_string(key.c_str());
+            vals[2]->val.string_val.data = util::copy_string(key.c_str(), key.size());
             vals[2]->val.string_val.length = key.size();
             vals[3] = eventval;
 
diff --git a/src/input/readers/raw/Raw.cc b/src/input/readers/raw/Raw.cc
index ed59c38ce6..5161843af0 100644
--- a/src/input/readers/raw/Raw.cc
+++ b/src/input/readers/raw/Raw.cc
@@ -679,11 +679,13 @@ bool Raw::DoUpdate() {
 
         Value** vals = new Value*[4];
         vals[0] = new Value(TYPE_STRING, true);
-        vals[0]->val.string_val.data = util::copy_string(Info().name);
-        vals[0]->val.string_val.length = strlen(Info().name);
+        auto val0_len = strlen(Info().name);
+        vals[0]->val.string_val.data = util::copy_string(Info().name, val0_len);
+        vals[0]->val.string_val.length = val0_len;
         vals[1] = new Value(TYPE_STRING, true);
-        vals[1]->val.string_val.data = util::copy_string(Info().source);
-        vals[1]->val.string_val.length = strlen(Info().source);
+        auto val1_len = strlen(Info().source);
+        vals[1]->val.string_val.data = util::copy_string(Info().source, val1_len);
+        vals[1]->val.string_val.length = val1_len;
         vals[2] = new Value(TYPE_COUNT, true);
         vals[2]->val.int_val = code;
         vals[3] = new Value(TYPE_BOOL, true);
diff --git a/src/logging/Manager.cc b/src/logging/Manager.cc
index 6f9d8f4e2e..01844e596c 100644
--- a/src/logging/Manager.cc
+++ b/src/logging/Manager.cc
@@ -803,14 +803,15 @@ bool Manager::Write(EnumVal* id, RecordVal* columns_arg) {
 
                     if ( const auto& val = filter->field_name_map->Find(fn) ) {
                         delete[] filter->fields[j]->name;
-                        filter->fields[j]->name = util::copy_string(val->AsStringVal()->CheckString());
+                        auto [data, len] = val->AsStringVal()->CheckStringWithSize();
+                        filter->fields[j]->name = util::copy_string(data, len);
                     }
                 }
                 arg_fields[j] = new threading::Field(*filter->fields[j]);
             }
 
             info = new WriterBackend::WriterInfo;
-            info->path = util::copy_string(path.c_str());
+            info->path = util::copy_string(path.c_str(), path.size());
             info->network_time = run_state::network_time;
 
             auto* filter_config_table = filter->config->AsTable();
@@ -821,7 +822,8 @@ bool Manager::Write(EnumVal* id, RecordVal* columns_arg) {
                 auto index = filter->config->RecreateIndex(*k);
                 string key = index->Idx(0)->AsString()->CheckString();
                 string value = v->GetVal()->AsString()->CheckString();
-                info->config.insert(std::make_pair(util::copy_string(key.c_str()), util::copy_string(value.c_str())));
+                info->config.emplace(util::copy_string(key.c_str(), key.size()),
+                                     util::copy_string(value.c_str(), value.size()));
             }
 
             // CreateWriter() will set the other fields in info.
@@ -883,14 +885,15 @@ threading::Value* Manager::ValToLogVal(std::optional<ZVal>& val, Type* ty) {
             const char* s = ty->AsEnumType()->Lookup(val->AsInt());
 
             if ( s ) {
-                lval->val.string_val.data = util::copy_string(s);
-                lval->val.string_val.length = strlen(s);
+                auto len = strlen(s);
+                lval->val.string_val.data = util::copy_string(s, len);
+                lval->val.string_val.length = len;
             }
 
             else {
                 auto err_msg = "enum type does not contain value:" + std::to_string(val->AsInt());
                 ty->Error(err_msg.c_str());
-                lval->val.string_val.data = util::copy_string("");
+                lval->val.string_val.data = util::copy_string("", 0);
                 lval->val.string_val.length = 0;
             }
             break;
@@ -935,9 +938,10 @@ threading::Value* Manager::ValToLogVal(std::optional<ZVal>& val, Type* ty) {
 
         case TYPE_FILE: {
             const File* f = val->AsFile();
-            string s = f->Name();
-            lval->val.string_val.data = util::copy_string(s.c_str());
-            lval->val.string_val.length = s.size();
+            const char* s = f->Name();
+            auto len = strlen(s);
+            lval->val.string_val.data = util::copy_string(s, len);
+            lval->val.string_val.length = len;
             break;
         }
 
@@ -946,8 +950,9 @@ threading::Value* Manager::ValToLogVal(std::optional<ZVal>& val, Type* ty) {
             const Func* f = val->AsFunc();
             f->Describe(&d);
             const char* s = d.Description();
-            lval->val.string_val.data = util::copy_string(s);
-            lval->val.string_val.length = strlen(s);
+            auto len = strlen(s);
+            lval->val.string_val.data = util::copy_string(s, len);
+            lval->val.string_val.length = len;
             break;
         }
 
diff --git a/src/logging/WriterBackend.cc b/src/logging/WriterBackend.cc
index fefde92af1..30a12e74f0 100644
--- a/src/logging/WriterBackend.cc
+++ b/src/logging/WriterBackend.cc
@@ -73,9 +73,7 @@ broker::data WriterBackend::WriterInfo::ToBroker() const {
     auto t = broker::table();
 
     for ( config_map::const_iterator i = config.begin(); i != config.end(); ++i ) {
-        auto key = std::string(i->first);
-        auto value = std::string(i->second);
-        t.insert(std::make_pair(key, value));
+        t.emplace(std::string{i->first}, std::string{i->second});
     }
 
     auto bppf = post_proc_func ? post_proc_func : "";
@@ -98,7 +96,7 @@ bool WriterBackend::WriterInfo::FromBroker(broker::data d) {
     if ( ! (bpath && brotation_base && brotation_interval && bnetwork_time && bconfig && bppf) )
         return false;
 
-    path = util::copy_string(bpath->c_str());
+    path = util::copy_string(bpath->c_str(), bpath->size());
     post_proc_func = util::copy_string(bppf->c_str());
     rotation_base = *brotation_base;
     rotation_interval = *brotation_interval;
@@ -111,7 +109,7 @@ bool WriterBackend::WriterInfo::FromBroker(broker::data d) {
         if ( ! (k && v) )
             return false;
 
-        auto p = std::make_pair(util::copy_string(k->c_str()), util::copy_string(v->c_str()));
+        auto p = std::make_pair(util::copy_string(k->c_str(), k->size()), util::copy_string(v->c_str(), v->size()));
         config.insert(p);
     }
 
diff --git a/src/script_opt/CPP/RuntimeInits.cc b/src/script_opt/CPP/RuntimeInits.cc
index d5757a776c..80c2337f63 100644
--- a/src/script_opt/CPP/RuntimeInits.cc
+++ b/src/script_opt/CPP/RuntimeInits.cc
@@ -405,7 +405,7 @@ int CPP_FieldMapping::ComputeOffset(InitsManager* im) const {
     if ( fm_offset < 0 ) { // field does not exist, create it
         fm_offset = r->NumFields();
 
-        auto id = util::copy_string(field_name.c_str());
+        auto id = util::copy_string(field_name.c_str(), field_name.size());
         auto type = im->Types(field_type);
 
         AttributesPtr attrs;
diff --git a/src/spicy/runtime-support.cc b/src/spicy/runtime-support.cc
index 58fa96041c..497abb91ea 100644
--- a/src/spicy/runtime-support.cc
+++ b/src/spicy/runtime-support.cc
@@ -146,7 +146,7 @@ TypePtr rt::create_record_type(const std::string& ns, const std::string& id,
             attrs->AddAttr(std::move(log_));
         }
 
-        decls->append(new TypeDecl(util::copy_string(f.id.c_str()), f.type, std::move(attrs)));
+        decls->append(new TypeDecl(util::copy_string(f.id.c_str(), f.id.size()), f.type, std::move(attrs)));
     }
 
     return make_intrusive<RecordType>(decls.release());
diff --git a/src/threading/MsgThread.cc b/src/threading/MsgThread.cc
index 83c55014ec..a1d2e5e3da 100644
--- a/src/threading/MsgThread.cc
+++ b/src/threading/MsgThread.cc
@@ -72,7 +72,7 @@ public:
     ReporterMessage(Type arg_type, MsgThread* thread, std::string_view arg_msg)
         : OutputMessage<MsgThread>("ReporterMessage", thread) {
         type = arg_type;
-        msg = util::copy_string(arg_msg.data());
+        msg = util::copy_string(arg_msg.data(), arg_msg.size());
     }
 
     ~ReporterMessage() override { delete[] msg; }
@@ -104,7 +104,7 @@ public:
     DebugMessage(DebugStream arg_stream, MsgThread* thread, std::string_view arg_msg)
         : OutputMessage<MsgThread>("DebugMessage", thread) {
         stream = arg_stream;
-        msg = util::copy_string(arg_msg.data());
+        msg = util::copy_string(arg_msg.data(), arg_msg.size());
     }
 
     ~DebugMessage() override { delete[] msg; }
diff --git a/src/threading/SerialTypes.cc b/src/threading/SerialTypes.cc
index c55c82378c..44cddf4636 100644
--- a/src/threading/SerialTypes.cc
+++ b/src/threading/SerialTypes.cc
@@ -30,7 +30,7 @@ bool Field::Read(detail::SerializationFormat* fmt) {
         if ( ! fmt->Read(&tmp_secondary_name, "secondary_name") )
             return false;
 
-        secondary_name = util::copy_string(tmp_secondary_name.c_str());
+        secondary_name = util::copy_string(tmp_secondary_name.c_str(), tmp_secondary_name.size());
     }
     else
         secondary_name = nullptr;
@@ -41,7 +41,7 @@ bool Field::Read(detail::SerializationFormat* fmt) {
     if ( ! success )
         return false;
 
-    name = util::copy_string(tmp_name.c_str());
+    name = util::copy_string(tmp_name.c_str(), tmp_name.size());
 
     type = static_cast<TypeTag>(t);
     subtype = static_cast<TypeTag>(st);
diff --git a/src/threading/formatters/Ascii.cc b/src/threading/formatters/Ascii.cc
index b296e5b8af..22ef1e8efb 100644
--- a/src/threading/formatters/Ascii.cc
+++ b/src/threading/formatters/Ascii.cc
@@ -287,7 +287,7 @@ Value* Ascii::ParseValue(const string& s, const string& name, TypeTag type, Type
                     // Remove the '/'s
                     candidate.erase(0, 1);
                     candidate.erase(candidate.size() - 1);
-                    val->val.pattern_text_val = util::copy_string(candidate.c_str());
+                    val->val.pattern_text_val = util::copy_string(candidate.c_str(), candidate.size());
                     break;
                 }
             }
diff --git a/src/util.cc b/src/util.cc
index 5ef75ae00e..152c12a3f7 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -1022,6 +1022,16 @@ std::string get_escaped_string(const char* str, size_t len, bool escape_all) {
     return get_escaped_string(&d, str, len, escape_all)->Description();
 }
 
+char* copy_string(const char* str, size_t len) {
+    if ( ! str )
+        return nullptr;
+
+    char* c = new char[len + 1];
+    memcpy(c, str, len);
+    c[len] = '\0';
+    return c;
+}
+
 char* copy_string(const char* s) {
     if ( ! s )
         return nullptr;
diff --git a/src/util.h b/src/util.h
index 8b89dd838c..3a69293ad2 100644
--- a/src/util.h
+++ b/src/util.h
@@ -330,6 +330,7 @@ std::vector<std::string>* tokenize_string(std::string_view input, std::string_vi
 
 std::vector<std::string_view> tokenize_string(std::string_view input, const char delim) noexcept;
 
+extern char* copy_string(const char* str, size_t len);
 extern char* copy_string(const char* s);
 extern bool streq(const char* s1, const char* s2);
 extern bool starts_with(std::string_view s, std::string_view beginning);
diff --git a/src/zeek-setup.cc b/src/zeek-setup.cc
index 12ecb51676..d215da56a8 100644
--- a/src/zeek-setup.cc
+++ b/src/zeek-setup.cc
@@ -434,15 +434,14 @@ static std::vector<std::string> get_script_signature_files() {
     std::vector<std::string> rval;
 
     // Parse rule files defined on the script level.
-    char* script_signature_files = util::copy_string(id::find_val("signature_files")->AsString()->CheckString());
+    auto script_signature_files = id::find_val("signature_files")->AsStringVal()->ToStdString();
 
-    char* tmp = script_signature_files;
+    char* tmp = script_signature_files.data();
     char* s;
     while ( (s = strsep(&tmp, " \t")) )
         if ( *s )
             rval.emplace_back(s);
 
-    delete[] script_signature_files;
     return rval;
 }
 
diff --git a/src/zeek.bif b/src/zeek.bif
index e4d59690ff..0ab356e829 100644
--- a/src/zeek.bif
+++ b/src/zeek.bif
@@ -448,7 +448,8 @@ static bool prepare_environment(zeek::TableVal* tbl, bool set)
 			return false;
 			}
 
-		char* tmp = zeek::util::copy_string(key->AsString()->CheckString());
+auto [data,len] = key->AsString()->CheckStringWithSize();
+		char* tmp = zeek::util::copy_string(data, len);
 		zeek::util::to_upper(tmp);
 		std::string var1 = zeek::util::fmt("ZEEK_ARG_%s", tmp);
 		delete [] tmp;
diff --git a/src/zeekygen/Target.cc b/src/zeekygen/Target.cc
index 1837ff73d6..519f4ccd24 100644
--- a/src/zeekygen/Target.cc
+++ b/src/zeekygen/Target.cc
@@ -439,9 +439,8 @@ vector<string> dir_contents_recursive(string dir) {
     while ( dir[dir.size() - 1] == '/' )
         dir.erase(dir.size() - 1, 1);
 
-    char* dir_copy = util::copy_string(dir.c_str());
     char** scan_path = new char*[2];
-    scan_path[0] = dir_copy;
+    scan_path[0] = dir.data();
     scan_path[1] = NULL;
 
     FTS* fts = fts_open(scan_path, FTS_NOCHDIR, 0);
@@ -449,7 +448,6 @@ vector<string> dir_contents_recursive(string dir) {
     if ( ! fts ) {
         reporter->Error("fts_open failure: %s", strerror(errno));
         delete[] scan_path;
-        delete[] dir_copy;
         return rval;
     }
 
@@ -467,7 +465,6 @@ vector<string> dir_contents_recursive(string dir) {
         reporter->Error("fts_close failure: %s", strerror(errno));
 
     delete[] scan_path;
-    delete[] dir_copy;
     return rval;
 }
 
diff --git a/testing/btest/plugins/reader-plugin/src/Foo.cc b/testing/btest/plugins/reader-plugin/src/Foo.cc
index 88d7070111..1c981e7b5a 100644
--- a/testing/btest/plugins/reader-plugin/src/Foo.cc
+++ b/testing/btest/plugins/reader-plugin/src/Foo.cc
@@ -73,7 +73,7 @@ zeek::threading::Value* Foo::EntryToVal(zeek::TypeTag type, zeek::TypeTag subtyp
 
         case zeek::TYPE_STRING: {
             std::string rnd = RandomString(10);
-            val->val.string_val.data = zeek::util::copy_string(rnd.c_str());
+            val->val.string_val.data = zeek::util::copy_string(rnd.c_str(), rnd.size());
             val->val.string_val.length = rnd.size();
             break;
         }