diff --git a/src/interpreter.c b/src/interpreter.c
index 8498e29..2b27c01 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -148,9 +148,16 @@ GroundVariable* findVariable(GroundVariable* head, const char *id) {
 }
 
 void deleteVariable(GroundVariable** head, GroundVariable *item) {
+    if (item == NULL) {
+        return;
+    }
     if (strcmp(item->id, "self") == 0) {
         return;
     }
+    if (item->freed) {
+        return;
+    }
+    item->freed = true;
     if (item->value.type == CUSTOM) {
         GroundObjectField* destructor = findField(*item->value.data.customVal, "destructor");
         if (destructor != NULL) {
@@ -175,6 +182,7 @@ void deleteVariable(GroundVariable** head, GroundVariable *item) {
             }
         }
     }
+    freeGroundValue(&item->value);
     HASH_DEL(*head, item);
     free(item);
 }
@@ -182,12 +190,12 @@ void deleteVariable(GroundVariable** head, GroundVariable *item) {
 void addVariable(GroundVariable **head, const char *id, GroundValue data) {
     GroundVariable* variable = findVariable(*head, id);
     if (variable) {
-        freeGroundValue(&variable->value);
         deleteVariable(head, variable);
     }
     GroundVariable* item = malloc(sizeof(GroundVariable));
     snprintf(item->id, MAX_ID_LEN, "%s", id);
     item->value = copyGroundValue(&data);
+    item->freed = false;
     HASH_ADD_STR(*head, id, item);
 }
 
@@ -1904,7 +1912,7 @@ GroundValue interpretGroundInstruction(GroundInstruction inst, GroundScope* scop
                             runtimeError(ARG_TYPE_MISMATCH, "Mismatched function argument types", in, currentInstruction);
                         }
                     } else {
-                        if (function->args[i].type != ANY || !checkFnTypes(&in->args.args[i + 1].value.value, &function->args[i])) {
+                        if (function->args[i].type != ANY && !checkFnTypes(&in->args.args[i + 1].value.value, &function->args[i])) {
                             runtimeError(ARG_TYPE_MISMATCH, "Mismatched function argument types", in, currentInstruction);
                         }
                     }
@@ -1934,7 +1942,7 @@ GroundValue interpretGroundInstruction(GroundInstruction inst, GroundScope* scop
                     if (in->args.args[i + 1].type != VALUE) {
                         runtimeError(ARG_TYPE_MISMATCH, "Expecting a Value", in, currentInstruction);
                     }
-                    if (function->args[i].type != ANY || !checkFnTypes(&in->args.args[i + 1].value.value, &function->args[i])) {
+                    if (function->args[i].type != ANY && !checkFnTypes(&in->args.args[i + 1].value.value, &function->args[i])) {
                         runtimeError(ARG_TYPE_MISMATCH, "Mismatched function argument types", in, currentInstruction);
                     }
                     addVariable(newScope.variables, function->args[i].name, in->args.args[i + 1].value.value);
@@ -2008,7 +2016,7 @@ GroundValue interpretGroundInstruction(GroundInstruction inst, GroundScope* scop
                             runtimeError(ARG_TYPE_MISMATCH, "Mismatched function argument types", in, currentInstruction);
                         }
                     } else {
-                        if (function->args[i].type != ANY || !checkFnTypes(&in->args.args[i + 2].value.value, &function->args[i])) {
+                        if (function->args[i].type != ANY && !checkFnTypes(&in->args.args[i + 2].value.value, &function->args[i])) {
                             runtimeError(ARG_TYPE_MISMATCH, "Mismatched function argument types", in, currentInstruction);
                         }
                     }
@@ -2063,7 +2071,7 @@ GroundValue interpretGroundInstruction(GroundInstruction inst, GroundScope* scop
                         runtimeError(ARG_TYPE_MISMATCH, "Expecting a Value", in, currentInstruction);
                     }
                     //if (in->args.args[i + 1].value.value.type != function->args[i].type) {
-                    if (function->args[i].type != ANY || !checkFnTypes(&in->args.args[i + 2].value.value, &function->args[i])) {
+                    if (function->args[i].type != ANY && !checkFnTypes(&in->args.args[i + 2].value.value, &function->args[i])) {
                         runtimeError(ARG_TYPE_MISMATCH, "Mismatched function argument types", in, currentInstruction);
                     }
                     addVariable(newScope.variables, function->args[i].name, in->args.args[i + 2].value.value);
diff --git a/src/types.h b/src/types.h
index 8c96cd4..c75fee9 100644
--- a/src/types.h
+++ b/src/types.h
@@ -107,6 +107,7 @@ typedef struct GroundVariable {
     char id[MAX_ID_LEN];
     GroundValue value;
     UT_hash_handle hh;
+    bool freed;
 } GroundVariable;
 
 typedef struct GroundScope {