diff --git a/src/vec3.zig b/src/vec3.zig
index e9cdd25..3079253 100644
--- a/src/vec3.zig
+++ b/src/vec3.zig
@@ -90,7 +90,7 @@ pub fn mat3Mul(a: Mat3F64, b: Mat3F64) Mat3F64 {
 pub fn mat3Det(a: Mat3F64) f64 {
     return a.row1.x() * (a.row2.y() * a.row3.z() - a.row2.z() * a.row3.y()) -
         a.row1.y() * (a.row2.x() * a.row3.z() - a.row2.z() * a.row3.x()) +
-        a.row1.y() * (a.row2.x() * a.row3.y() - a.row2.y() * a.row3.x());
+        a.row1.z() * (a.row2.x() * a.row3.y() - a.row2.y() * a.row3.x());
 }
 
 pub fn mat3Inv(a: Mat3F64) Mat3F64 {
@@ -105,7 +105,7 @@ pub fn mat3Inv(a: Mat3F64) Mat3F64 {
     );
     const row2 = vec3Scale(
         .init(
-            a.row2.z() * a.row3.x() + a.row2.x() * a.row3.z(),
+            a.row2.z() * a.row3.x() - a.row2.x() * a.row3.z(),
             a.row1.x() * a.row3.z() - a.row1.z() * a.row3.x(),
             a.row1.z() * a.row2.x() - a.row1.x() * a.row2.z(),
         ),
@@ -113,7 +113,7 @@ pub fn mat3Inv(a: Mat3F64) Mat3F64 {
     );
     const row3 = vec3Scale(
         .init(
-            a.row2.x() * a.row3.y() + a.row2.y() * a.row3.x(),
+            a.row2.x() * a.row3.y() - a.row2.y() * a.row3.x(),
             a.row1.y() * a.row3.x() - a.row1.x() * a.row3.y(),
             a.row1.x() * a.row2.y() - a.row1.y() * a.row2.x(),
         ),
@@ -321,30 +321,30 @@ test "Mat3 mul works" {
 test "mat determinant works" {
     const a: Mat3F64 = .{
         .row1 = Vec3F64.init(1, 2, 3),
-        .row2 = Vec3F64.init(0, 1, 5),
-        .row3 = Vec3F64.init(0, 0, 9),
+        .row2 = Vec3F64.init(4, 1, 5),
+        .row3 = Vec3F64.init(3, 1, 9),
     };
-    try std.testing.expectApproxEqAbs(9, mat3Det(a), 1e-12);
+    try std.testing.expectApproxEqAbs(-35, mat3Det(a), 1e-12);
 }
 
 test "mat inverse works" {
     const a: Mat3F64 = .{
         .row1 = Vec3F64.init(1, 2, 3),
-        .row2 = Vec3F64.init(0, 1, 5),
-        .row3 = Vec3F64.init(0, 0, 9),
+        .row2 = Vec3F64.init(4, 1, 5),
+        .row3 = Vec3F64.init(3, 1, 9),
     };
 
     const ainv = mat3Inv(a);
 
-    try std.testing.expectApproxEqAbs(1, ainv.row1.x(), 1e-12);
-    try std.testing.expectApproxEqAbs(-2, ainv.row1.y(), 1e-12);
-    try std.testing.expectApproxEqAbs(7.0 / 9.0, ainv.row1.z(), 1e-12);
-    try std.testing.expectApproxEqAbs(0, ainv.row2.x(), 1e-12);
-    try std.testing.expectApproxEqAbs(1, ainv.row2.y(), 1e-12);
-    try std.testing.expectApproxEqAbs(-5.0 / 9.0, ainv.row2.z(), 1e-12);
-    try std.testing.expectApproxEqAbs(0, ainv.row3.x(), 1e-12);
-    try std.testing.expectApproxEqAbs(0, ainv.row3.y(), 1e-12);
-    try std.testing.expectApproxEqAbs(1.0 / 9.0, ainv.row3.z(), 1e-12);
+    try std.testing.expectApproxEqAbs(-4.0 / 35.0, ainv.row1.x(), 1e-12);
+    try std.testing.expectApproxEqAbs(3.0 / 7.0, ainv.row1.y(), 1e-12);
+    try std.testing.expectApproxEqAbs(-1.0 / 5.0, ainv.row1.z(), 1e-12);
+    try std.testing.expectApproxEqAbs(3.0 / 5.0, ainv.row2.x(), 1e-12);
+    try std.testing.expectApproxEqAbs(0, ainv.row2.y(), 1e-12);
+    try std.testing.expectApproxEqAbs(-1.0 / 5.0, ainv.row2.z(), 1e-12);
+    try std.testing.expectApproxEqAbs(-1.0 / 35.0, ainv.row3.x(), 1e-12);
+    try std.testing.expectApproxEqAbs(-1.0 / 7.0, ainv.row3.y(), 1e-12);
+    try std.testing.expectApproxEqAbs(1.0 / 5.0, ainv.row3.z(), 1e-12);
 }
 test "vec3 mul mat3 works" {
     const b: Mat3F64 = .{