diff --git a/internal/shader/expr.go b/internal/shader/expr.go
index c55a52810..a5b4ee2fa 100644
--- a/internal/shader/expr.go
+++ b/internal/shader/expr.go
@@ -34,34 +34,6 @@ func canTruncateToFloat(v gconstant.Value) bool {
 	return gconstant.ToFloat(v).Kind() != gconstant.Unknown
 }
 
-func isValidForModOp(lhs, rhs *shaderir.Expr, lhst, rhst shaderir.Type) bool {
-	isInt := func(s *shaderir.Expr, t shaderir.Type) bool {
-		if t.Main == shaderir.Int {
-			return true
-		}
-		if s.Const == nil {
-			return false
-		}
-		if s.Const.Kind() == gconstant.Int {
-			return true
-		}
-		if canTruncateToInteger(s.Const) {
-			return true
-		}
-		return false
-	}
-
-	if isInt(lhs, lhst) {
-		return isInt(rhs, rhst)
-	}
-
-	if lhst.Main == shaderir.IVec2 || lhst.Main == shaderir.IVec3 || lhst.Main == shaderir.IVec4 {
-		return lhst.Equal(&rhst) || isInt(rhs, rhst)
-	}
-
-	return false
-}
-
 var textureVariableRe = regexp.MustCompile(`\A__t(\d+)\z`)
 
 func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, markLocalVariableUsed bool) ([]shaderir.Expr, []shaderir.Type, []shaderir.Stmt, bool) {
@@ -227,32 +199,12 @@ func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, mar
 			t = rhst
 		case rhst.Main == shaderir.Float:
 			t = lhst
-		case op2 == shaderir.MatrixMul && (lhst.Main == shaderir.Vec2 && rhst.Main == shaderir.Mat2 ||
-			lhst.Main == shaderir.Mat2 && rhst.Main == shaderir.Vec2):
-			t = shaderir.Type{Main: shaderir.Vec2}
-		case op2 == shaderir.MatrixMul && (lhst.Main == shaderir.Vec3 && rhst.Main == shaderir.Mat3 ||
-			lhst.Main == shaderir.Mat3 && rhst.Main == shaderir.Vec3):
-			t = shaderir.Type{Main: shaderir.Vec3}
-		case op2 == shaderir.MatrixMul && (lhst.Main == shaderir.Vec4 && rhst.Main == shaderir.Mat4 ||
-			lhst.Main == shaderir.Mat4 && rhst.Main == shaderir.Vec4):
-			t = shaderir.Type{Main: shaderir.Vec4}
+		case op2 == shaderir.MatrixMul && lhst.IsVector() && rhst.IsMatrix():
+			t = lhst
+		case op2 == shaderir.MatrixMul && lhst.IsMatrix() && rhst.IsVector():
+			t = rhst
 		default:
-			cs.addError(e.Pos(), fmt.Sprintf("invalid expression: %s %s %s", lhst.String(), e.Op, rhst.String()))
-			return nil, nil, nil, false
-		}
-
-		// For `%`, both types must be deducible to integers.
-		if op2 == shaderir.ModOp {
-			if !isValidForModOp(&lhs[0], &rhs[0], lhst, rhst) {
-				var wrongType shaderir.Type
-				if lhst.Main != shaderir.Int {
-					wrongType = lhst
-				} else {
-					wrongType = rhst
-				}
-				cs.addError(e.Pos(), fmt.Sprintf("invalid operation: operator %% not defined on %s", wrongType.String()))
-				return nil, nil, nil, false
-			}
+			panic(fmt.Sprintf("shaderir: invalid expression: %s %s %s", lhst.String(), e.Op, rhst.String()))
 		}
 
 		return []shaderir.Expr{
diff --git a/internal/shaderir/check.go b/internal/shaderir/check.go
index 66c4d4f60..ebb899264 100644
--- a/internal/shaderir/check.go
+++ b/internal/shaderir/check.go
@@ -69,25 +69,6 @@ func ResolveUntypedConstsForBinaryOp(lhs, rhs constant.Value, lhst, rhst Type) (
 }
 
 func AreValidTypesForBinaryOp(op Op, lhs, rhs *Expr, lhst, rhst Type) bool {
-	if op == AndAnd || op == OrOr {
-		return lhst.Main == Bool && rhst.Main == Bool
-	}
-
-	if op == VectorEqualOp || op == VectorNotEqualOp {
-		return lhst.IsVector() && rhst.IsVector() && lhst.Equal(&rhst)
-	}
-
-	// Comparing matrices are forbidden (#2187).
-	if op == LessThanOp || op == LessThanEqualOp || op == GreaterThanOp || op == GreaterThanEqualOp || op == EqualOp || op == NotEqualOp {
-		if lhst.IsMatrix() || rhst.IsMatrix() {
-			return false
-		}
-	}
-
-	if op == Div && rhst.IsMatrix() {
-		return false
-	}
-
 	// If both are untyped consts, compare the constants and try to truncate them if necessary.
 	if lhst.Main == None && rhst.Main == None {
 		// Assume that the constant types are already adjusted.
@@ -95,6 +76,10 @@ func AreValidTypesForBinaryOp(op Op, lhs, rhs *Expr, lhst, rhst Type) bool {
 			panic("shaderir: const types for a binary op must be adjusted")
 		}
 
+		if op == AndAnd || op == OrOr {
+			return lhs.Const.Kind() == constant.Bool && rhs.Const.Kind() == constant.Bool
+		}
+
 		// For %, both operands must be integers if both are constants. Truncatable to an integer is not enough.
 		if op == ModOp {
 			return lhs.Const.Kind() == constant.Int && rhs.Const.Kind() == constant.Int
@@ -107,25 +92,73 @@ func AreValidTypesForBinaryOp(op Op, lhs, rhs *Expr, lhst, rhst Type) bool {
 		panic("shaderir: cannot resolve untyped values")
 	}
 
+	if op == AndAnd || op == OrOr {
+		return lhst.Main == Bool && rhst.Main == Bool
+	}
+
+	if op == VectorEqualOp || op == VectorNotEqualOp {
+		return lhst.IsVector() && rhst.IsVector() && lhst.Equal(&rhst)
+	}
+
+	// Comparing matrices are forbidden (#2187).
+	if op == LessThanOp || op == LessThanEqualOp || op == GreaterThanOp || op == GreaterThanEqualOp || op == EqualOp || op == NotEqualOp {
+		if lhst.IsMatrix() || rhst.IsMatrix() {
+			return false
+		}
+		return lhst.Equal(&rhst)
+	}
+
+	if op == Div && rhst.IsMatrix() {
+		return false
+	}
+
+	if op == ModOp {
+		if lhst.Main == IVec2 && rhst.Main == IVec2 {
+			return true
+		}
+		if lhst.Main == IVec3 && rhst.Main == IVec3 {
+			return true
+		}
+		if lhst.Main == IVec4 && rhst.Main == IVec4 {
+			return true
+		}
+		return (lhst.Main == Int || lhst.isIntVector()) && rhst.Main == Int
+	}
+
 	if lhst.Equal(&rhst) {
 		return true
 	}
 
 	if op == MatrixMul {
-		if lhst.IsMatrix() && (rhst.isFloatVector() || rhst.Main == Float) {
-			// TODO: Check dimensions
+		if lhst.IsMatrix() && rhst.Main == Float {
 			return true
 		}
-		if rhst.IsMatrix() && (lhst.isFloatVector() || lhst.Main == Float) {
-			// TODO: Check dimensions
+		if lhst.Main == Mat2 && rhst.Main == Vec2 {
+			return true
+		}
+		if lhst.Main == Mat3 && rhst.Main == Vec3 {
+			return true
+		}
+		if lhst.Main == Mat4 && rhst.Main == Vec4 {
+			return true
+		}
+		if lhst.Main == Float && rhst.IsMatrix() {
+			return true
+		}
+		if lhst.Main == Vec2 && rhst.Main == Mat2 {
+			return true
+		}
+		if lhst.Main == Vec3 && rhst.Main == Mat3 {
+			return true
+		}
+		if lhst.Main == Vec4 && rhst.Main == Mat4 {
 			return true
 		}
 		return false
 	}
 
 	if op == Div {
-		if lhst.IsMatrix() && (rhst.isFloatVector() || rhst.Main == Float) {
-			// TODO: Check dimensions
+		if lhst.IsMatrix() && rhst.Main == Float {
 			return true
 		}
 		// fallback