diff --git a/tools/qfcc/include/type.h b/tools/qfcc/include/type.h
index 7e375f573..0522602b9 100644
--- a/tools/qfcc/include/type.h
+++ b/tools/qfcc/include/type.h
@@ -125,6 +125,7 @@ const char *encode_params (type_t *type);
 void encode_type (struct dstring_s *encoding, type_t *type);
 type_t *parse_type (const char *str);
 int is_scalar (type_t *type);
+int is_math (type_t *type);
 int is_struct (type_t *type);
 int is_class (type_t *type);
 int is_array (type_t *type);
diff --git a/tools/qfcc/source/expr.c b/tools/qfcc/source/expr.c
index 45c5363dc..2c6449582 100644
--- a/tools/qfcc/source/expr.c
+++ b/tools/qfcc/source/expr.c
@@ -1308,6 +1308,8 @@ unary_expr (int op, expr_t *e)
 		return e;
 	switch (op) {
 		case '-':
+			if (!is_math (get_type (e)))
+				return error (e, "invalid type for unary +");
 			if (is_constant (e)) {
 				switch (extract_type (e)) {
 					case ev_string:
@@ -1315,7 +1317,7 @@ unary_expr (int op, expr_t *e)
 					case ev_field:
 					case ev_func:
 					case ev_pointer:
-						return error (e, "invalid type for unary -");
+						internal_error (e, "type check failed!");
 					case ev_float:
 						return new_float_expr (-expr_float (e));
 					case ev_vector:
@@ -1493,7 +1495,9 @@ bitnot_expr:
 			e->e.expr.type = get_type (e->e.expr.e1)->t.fldptr.type;
 			return e;
 		case '+':
-			return e;			// FIXME typechecking
+			if (!is_math (get_type (e)))
+				return error (e, "invalid type for unary +");
+			return e;
 	}
 	internal_error (e, 0);
 }
diff --git a/tools/qfcc/source/type.c b/tools/qfcc/source/type.c
index 0efca005d..4a1ccd67e 100644
--- a/tools/qfcc/source/type.c
+++ b/tools/qfcc/source/type.c
@@ -73,6 +73,9 @@ type_t      type_pointer = { ev_pointer, "pointer", ty_none, {{&type_void}} };
 type_t      type_quaternion = { ev_quat, "quaternion" };
 type_t      type_integer = { ev_integer, "integer" };
 type_t      type_short = { ev_short, "short" };
+
+type_t     *type_nil;
+
 // these will be built up further
 type_t      type_id = { ev_pointer, "id" };
 type_t      type_Class = { ev_pointer, "Class" };
@@ -637,6 +640,14 @@ is_scalar (type_t *type)
 	return 0;
 }
 
+int
+is_math (type_t *type)
+{
+	etype_t     t = type->type;
+
+	return t == ev_vector || t == ev_quat || is_scalar (type);
+}
+
 int
 is_struct (type_t *type)
 {
@@ -844,6 +855,7 @@ init_types (void)
 		{0, 0}
 	};
 
+	type_nil = &type_quaternion;
 	if (options.code.progsversion == PROG_ID_VERSION) {
 		// vector can't be part of .zero for v6 progs because for v6 progs,
 		// .zero is only one word wide.
@@ -851,6 +863,7 @@ init_types (void)
 		// v6 progs don't have quaternions
 		zero_struct[8].name = 0;
 		param_struct[8].name = 0;
+		type_nil = &type_vector;
 	}
 
 	make_structure (0, 'u', zero_struct, &type_zero);