diff --git a/lex.c b/lex.c
index 3f3d274..3184650 100644
--- a/lex.c
+++ b/lex.c
@@ -2,6 +2,8 @@
 
 #include "util.h"
 
+#define TAB_WIDTH 4
+
 typedef struct Pos {
 	size_t ln, col;     /* current position */
 	size_t m_ln, m_col; /* marked position */
@@ -17,7 +19,9 @@ static void consume(Pos *p, char c) {
 	if (c == '\n') {
 		p->ln++;
 		p->col = 1;
-	} else
+	} else if (c == '\t')
+		p->col += TAB_WIDTH;
+	else
 		p->col++;
 }
 
diff --git a/parse.c b/parse.c
index a3cb3d6..819e815 100644
--- a/parse.c
+++ b/parse.c
@@ -292,6 +292,7 @@ static ExprRet expr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *parent_sc,
 				Value *arg_vals = args_len ? xmalloc(sizeof(Value) * args_len) : NULL;
 				for (size_t i = 0; i < args_len; i++)
 					arg_vals[i] = args[i].Literal;
+				mark_err(&func_ident->tok);
 				func_ident->tok = (Tok) {
 					.kind = TokVal,
 					.Val = func.func(arg_vals),
@@ -348,6 +349,7 @@ static ExprRet expr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *parent_sc,
 			if (v->kind == TokVal) {
 				/* immediately perform operation */
 				t->tok.kind = TokVal;
+				mark_err(&t->tok);
 				TRY_RET(t->tok.Val = eval_unary(unary_op, &v->Val), (ExprRet){0});
 			} else {
 				size_t res_addr = is_last_operation ? 0 : sc.mem_addr++;
@@ -472,6 +474,7 @@ static ExprRet expr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *parent_sc,
 				Value *lhs_val = swap_operands ? &rhs->Val : &lhs->Val;
 				Value *rhs_val = swap_operands ? &lhs->Val : &rhs->Val;
 				lhs->kind = TokVal;
+				mark_err(l_op);
 				TRY_RET(lhs->Val = eval_binary(instr, lhs_val, rhs_val), (ExprRet){0});
 			} else {
 				bool is_last_operation = t == start && r_op_prec == PREC_DELIM;
@@ -532,6 +535,8 @@ static void expr_into_addr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *par
 		IRParam res;
 		TRY(res = tok_to_irparam(parent_sc, &t->tok));
 		irtoks_app(out_ir, (IRTok){
+			.ln = t->tok.ln,
+			.col = t->tok.col,
 			.instr = IRSet,
 			.Unary = {
 				.addr = addr,
diff --git a/runtime.c b/runtime.c
index a94b1f4..2cf2d1f 100644
--- a/runtime.c
+++ b/runtime.c
@@ -35,7 +35,7 @@ Value eval_binary(IRInstr instr, const Value *lhs, const Value *rhs) {
 					.Float = res,
 				};
 			} else {
-				set_err("Unsupported types for operation '%s'", irinstr_str[instr]);
+				set_err("Unsupported types for operation '%s': %s and %s", irinstr_str[instr], type_str[lhs->type.kind], type_str[rhs->type.kind]);
 				return (Value){0};
 			}
 		}
@@ -58,7 +58,7 @@ Value eval_binary(IRInstr instr, const Value *lhs, const Value *rhs) {
 					default: ASSERT_UNREACHED();
 				};
 			} else {
-				set_err("Unsupported types for operation '%s'", irinstr_str[instr]);
+				set_err("Unsupported types for operation '%s': %s and %s", irinstr_str[instr], type_str[lhs->type.kind], type_str[rhs->type.kind]);
 				return (Value){0};
 			}
 			return (Value){
@@ -93,14 +93,14 @@ Value eval_unary(IRInstr instr, const Value *v) {
 			else if (v->type.kind == TypeFloat)
 				return (Value){ .type.kind = TypeFloat, .Float = -v->Float };
 			else {
-				set_err("Unsupported type for operation '%s'", irinstr_str[instr]);
+				set_err("Unsupported type for operation '%s': %s", irinstr_str[instr], type_str[v->type.kind]);
 				return (Value){0};
 			}
 		case IRNot:
 			if (v->type.kind == TypeBool) {
 				return (Value){ .type.kind = TypeBool, .Bool = !v->Bool };
 			} else {
-				set_err("Unsupported type for operation '%s'", irinstr_str[instr]);
+				set_err("Unsupported type for operation '%s': %s", irinstr_str[instr], type_str[v->type.kind]);
 				return (Value){0};
 			}
 		default:
diff --git a/tok.c b/tok.c
index f76d69e..63215ae 100644
--- a/tok.c
+++ b/tok.c
@@ -14,6 +14,15 @@ size_t type_size[TypeEnumSize] = {
 	[TypeArr]   = sizeof(((Value*)NULL)->Arr),
 };
 
+const char *type_str[TypeEnumSize] = {
+	[TypeVoid]  = "void",
+	[TypeFloat] = "float",
+	[TypeInt]   = "int",
+	[TypeBool]  = "bool",
+	[TypeChar]  = "char",
+	[TypeArr]   = "arr",
+};
+
 void print_value(const Value *v, bool raw) {
 	switch (v->type.kind) {
 		case TypeVoid:
diff --git a/tok.h b/tok.h
index 1380ab6..32fe39d 100644
--- a/tok.h
+++ b/tok.h
@@ -22,6 +22,7 @@ typedef struct Type {
 } Type;
 
 extern size_t type_size[TypeEnumSize];
+extern const char *type_str[TypeEnumSize];
 
 typedef struct Value {
 	Type type;