diff --git a/bin/build.js b/bin/build.js
index 8737c49..cd5454c 100755
--- a/bin/build.js
+++ b/bin/build.js
@@ -17,6 +17,7 @@ p.property('ptr', 'trigger');
 p.property('ptr', 'triee');
 p.property('ptr', 'lifee');
 p.property('ptr', 'info');
+p.property('ptr', 'tmpStr');
 p.property('i32', 'stackPointer');
 p.property('ptr', 'id');
 p.property('ptr', 'napi_env');
diff --git a/vcd.c b/vcd.c
index 61eb7f6..1c53078 100644
--- a/vcd.c
+++ b/vcd.c
@@ -123,10 +123,12 @@ METHOD(init) {
   ASSERT_OBJECT(args[2], state->info)
 
   static char triggerString [4096] = "       ";
+  static char tmpStr [4096] = "       ";
 
   state->trigger = triggerString;
   state->reason = "NO REASON";
   state->napi_env = env;
+  state->tmpStr = tmpStr;
 
   napi_value status;
   ASSERT(status, napi_create_string_latin1(env, "declaration", NAPI_AUTO_LENGTH, &status))
diff --git a/vcd_spans.c b/vcd_spans.c
index 45e47ba..b308ed4 100644
--- a/vcd_spans.c
+++ b/vcd_spans.c
@@ -8,6 +8,17 @@
         napi_throw(env, val); \
     }
 
+void strcopy(const unsigned char* p, const unsigned char* endp, unsigned char* dst) {
+  unsigned char* src;
+  src = p;
+  while (src < (endp - 1)) {
+    *dst = *src;
+    src++;
+    dst++;
+  }
+  *dst = 0;
+}
+
 // FIXME use a better structure to match strings
 int stringEq (
   const unsigned char* gold, // search pattern
@@ -60,15 +71,16 @@ int commandSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char
   return 0;
 }
 
-int scopeIdentifierSpan(vcd_parser_t* state, const unsigned char* p, /* FIXME const */ unsigned char* endp) {
+int scopeIdentifierSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char* endp) {
   napi_env env = state->napi_env;
-  *(endp - 1) = 0; // FIXME NULL termination of ASCII string
+  // *(endp - 1) = 0; // FIXME NULL termination of ASCII string
+  strcopy(p, endp, state->tmpStr);
   napi_value name, obj, stack, top;
   ASSERT(name, napi_create_string_latin1(env, (char*)p, (endp - p - 1), &name))
   ASSERT(obj, napi_create_object(env, &obj))
   ASSERT(state->info, napi_get_named_property(env, state->info, "stack", &stack))
   ASSERT(top, napi_get_element(env, stack, state->stackPointer, &top))
-  ASSERT(top, napi_set_named_property(env, top, p, obj))
+  ASSERT(top, napi_set_named_property(env, top, state->tmpStr, obj))
   state->stackPointer += 1;
   ASSERT(top, napi_set_element(env, stack, state->stackPointer, obj))
   return 0;
@@ -81,18 +93,21 @@ int varSizeSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char
 
 int varIdSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char* endp) {
   napi_env env = state->napi_env;
-  napi_value val;
-  ASSERT(state->id, napi_create_string_latin1(env, (char*)p, (endp - p - 1), &state->id))
+  napi_value varId;
+  ASSERT(varId, napi_create_string_latin1(env, (char*)p, (endp - p - 1), &varId))
+  ASSERT(state->info, napi_set_named_property(env, state->info, "varId", varId))
   return 0;
 }
 
-int varNameSpan(vcd_parser_t* state, const unsigned char* p, /* FIXME const */ unsigned char* endp) {
+int varNameSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char* endp) {
   napi_env env = state->napi_env;
-  *(endp - 1) = 0; // FIXME NULL termination of ASCII string
-  napi_value stack, top;
+  // *(endp - 1) = 0; // FIXME NULL termination of ASCII string
+  strcopy(p, endp, state->tmpStr);
+  napi_value stack, top, varId;
   ASSERT(state->info, napi_get_named_property(env, state->info, "stack", &stack))
   ASSERT(top, napi_get_element(env, stack, state->stackPointer, &top))
-  ASSERT(state->info, napi_set_named_property(env, top, p, state->id))
+  ASSERT(state->info, napi_get_named_property(env, state->info, "varId", &varId))
+  ASSERT(state->info, napi_set_named_property(env, top, state->tmpStr, varId))
   return 0;
 }