diff --git a/rcbasic_build/parser.h b/rcbasic_build/parser.h
index 58d1b03..5747682 100755
--- a/rcbasic_build/parser.h
+++ b/rcbasic_build/parser.h
@@ -6195,15 +6195,23 @@ bool check_rule()
                     }
                 }
                 else
-                {
-                    switch(var_type)
-                    {
-                        case ID_TYPE_NUM:
-                            vm_asm.push_back("mov !" + rc_intToString(id[var_id_index].vec_pos) + " " + expr_result);
-                            break;
-                        case ID_TYPE_STR:
-                            vm_asm.push_back("mov$ !" + rc_intToString(id[var_id_index].vec_pos) + " " + expr_result);
-                            break;
+                {
+                    if(var_id_index >= 0 && var_id_index < id.size())
+                    {
+                        switch(var_type)
+                        {
+                            case ID_TYPE_NUM:
+                                vm_asm.push_back("mov !" + rc_intToString(id[var_id_index].vec_pos) + " " + expr_result);
+                                break;
+                            case ID_TYPE_STR:
+                                vm_asm.push_back("mov$ !" + rc_intToString(id[var_id_index].vec_pos) + " " + expr_result);
+                                break;
+                        }
+                    }
+                    else
+                    {
+                        rc_setError("Identifier \"" + var_id + "\" could not be resolved");
+                        return false;
                     }
                 }
 
diff --git a/rcbasic_build/rcbasic_build.depend b/rcbasic_build/rcbasic_build.depend
index 08c9060..2637b70 100755
--- a/rcbasic_build/rcbasic_build.depend
+++ b/rcbasic_build/rcbasic_build.depend
@@ -1,5 +1,5 @@
 # depslib dependency file v1.0
-1769580634 source:/home/n00b/Projects/RCBASIC4/rcbasic_build/main.cpp
+1770701118 source:/home/n00b/Projects/RCBASIC4/rcbasic_build/main.cpp
 	<iostream>
 	<stack>
 	<vector>
@@ -37,7 +37,7 @@
 1752004854 /home/n00b/Projects/RCBASIC4/rcbasic_build/constants.h
 	<vector>
 
-1758412944 /home/n00b/Projects/RCBASIC4/rcbasic_build/parser.h
+1770926352 /home/n00b/Projects/RCBASIC4/rcbasic_build/parser.h
 	"tokenizer.h"
 	"identifier.h"
 	"rc_global.h"