diff --git a/src/evaluate/operator.rs b/src/evaluate/operator.rs
index bc77de4..1268554 100644
--- a/src/evaluate/operator.rs
+++ b/src/evaluate/operator.rs
@@ -162,6 +162,11 @@ pub fn eval_operator(context: &mut Context, g: &Expression) -> Result<Option<Exp
 					if va.fract() != Quantity::new_rational(0f64).unwrap() { return Err((*la + *lb + *op_loc, DaisyError::BadMath)); }
 					if vb.fract() != Quantity::new_rational(0f64).unwrap() { return Err((*la + *lb + *op_loc, DaisyError::BadMath)); }
 
+
+					let o = va.clone() % vb.clone();
+					if o.is_nan() {return Err((*la + *lb + *op_loc, DaisyError::BadMath));}
+
+
 					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, va.clone() % vb.clone())));
 				} else { return Ok(None); }
 			} else { return Ok(None); }
diff --git a/src/quantity/scalar/floatbase.rs b/src/quantity/scalar/floatbase.rs
index 37d0d5e..2a4792f 100644
--- a/src/quantity/scalar/floatbase.rs
+++ b/src/quantity/scalar/floatbase.rs
@@ -244,7 +244,7 @@ impl Rem<FloatBase> for FloatBase {
 			(!modulus.fract().unwrap().is_zero())
 		} { panic!() }
 
-		FloatBase{val : self.val.fract() % modulus.val.fract()}
+		FloatBase{val : self.val.trunc() % modulus.val.trunc()}
 	}
 }
 
diff --git a/src/quantity/scalar/scalar.rs b/src/quantity/scalar/scalar.rs
index 514e575..756e5bb 100644
--- a/src/quantity/scalar/scalar.rs
+++ b/src/quantity/scalar/scalar.rs
@@ -186,7 +186,7 @@ impl Scalar {
 	pub fn is_nan(&self) -> bool {
 		match self {
 			Scalar::Float {v} => {v.val.is_nan()},
-			Scalar::Rational {..} => {panic!()}
+			Scalar::Rational {..} => {false}
 		}
 	}
 
diff --git a/src/tests.rs b/src/tests.rs
index 0f41c8d..cf30e25 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -162,6 +162,7 @@ fn operators() {
 
 	good_expr("2", "6/3");
 	good_expr("2", "5%3");
+	good_expr("4", "2^5 mod 7");
 	good_expr("8", "5+3");
 	good_expr("64", "4^3");
 	good_expr("64", "4 ^ 3");