diff --git a/ports/geckolib/values.rs b/ports/geckolib/values.rs
index ee24be7565c..c6931d9a4a4 100644
--- a/ports/geckolib/values.rs
+++ b/ports/geckolib/values.rs
@@ -56,6 +56,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_auto(&mut self) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Auto;
         unsafe { *self.mValue.mInt.as_mut() = 0; }
     }
@@ -66,6 +67,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_normal(&mut self) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Normal;
         unsafe { *self.mValue.mInt.as_mut() = 0; }
     }
@@ -76,6 +78,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_coord(&mut self, val: Au) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Coord;
         unsafe { *self.mValue.mInt.as_mut() = val.0; }
     }
@@ -91,6 +94,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_int(&mut self, val: i32) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Integer;
         unsafe { *self.mValue.mInt.as_mut() = val; }
     }
@@ -106,6 +110,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_enum(&mut self, val: i32) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Enumerated;
         unsafe { *self.mValue.mInt.as_mut() = val; }
     }
@@ -121,6 +126,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_percent(&mut self, val: f32) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Percent;
         unsafe { *self.mValue.mFloat.as_mut() = val; }
     }
@@ -136,6 +142,7 @@ impl StyleCoordHelpers for nsStyleCoord {
 
     #[inline]
     fn set_factor(&mut self, val: f32) {
+        unsafe { self.mValue.reset(&mut self.mUnit)};
         self.mUnit = nsStyleUnit::eStyleUnit_Factor;
         unsafe { *self.mValue.mFloat.as_mut() = val; }
     }
@@ -157,6 +164,7 @@ pub trait GeckoStyleCoordConvertible : Sized {
 
 impl GeckoStyleCoordConvertible for LengthOrPercentage {
     fn to_gecko_style_coord(&self, unit: &mut nsStyleUnit, union: &mut nsStyleUnion) {
+        unsafe { union.reset(unit) };
         match *self {
             LengthOrPercentage::Length(au) => {
                 *unit = nsStyleUnit::eStyleUnit_Coord;
@@ -166,7 +174,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentage {
                 *unit = nsStyleUnit::eStyleUnit_Percent;
                 unsafe { *union.mFloat.as_mut() = p; }
             },
-            LengthOrPercentage::Calc(_) => unimplemented!(),
+            LengthOrPercentage::Calc(calc) => unsafe {union.set_calc_value(unit, calc.into()) },
         };
     }
 
@@ -177,7 +185,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentage {
             nsStyleUnit::eStyleUnit_Percent
                 => Some(LengthOrPercentage::Percentage(unsafe { *union.mFloat.as_ref() })),
             nsStyleUnit::eStyleUnit_Calc
-                => unimplemented!(),
+                => Some(LengthOrPercentage::Calc(unsafe { union.get_calc().into()})),
             _ => None,
         }
     }
@@ -185,6 +193,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentage {
 
 impl GeckoStyleCoordConvertible for LengthOrPercentageOrAuto {
     fn to_gecko_style_coord(&self, unit: &mut nsStyleUnit, union: &mut nsStyleUnion) {
+        unsafe { union.reset(unit) };
         match *self {
             LengthOrPercentageOrAuto::Length(au) => {
                 *unit = nsStyleUnit::eStyleUnit_Coord;
@@ -198,7 +207,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentageOrAuto {
                 *unit = nsStyleUnit::eStyleUnit_Auto;
                 unsafe { *union.mInt.as_mut() = 0; }
             },
-            LengthOrPercentageOrAuto::Calc(_) => unimplemented!(),
+            LengthOrPercentageOrAuto::Calc(calc) => unsafe {union.set_calc_value(unit, calc.into()) },
         };
     }
 
@@ -211,7 +220,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentageOrAuto {
             nsStyleUnit::eStyleUnit_Percent
                 => Some(LengthOrPercentageOrAuto::Percentage(unsafe { *union.mFloat.as_ref() })),
             nsStyleUnit::eStyleUnit_Calc
-                => unimplemented!(),
+                => Some(LengthOrPercentageOrAuto::Calc(unsafe { union.get_calc().into()})),
             _ => None,
         }
     }
@@ -219,6 +228,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentageOrAuto {
 
 impl GeckoStyleCoordConvertible for LengthOrPercentageOrNone {
     fn to_gecko_style_coord(&self, unit: &mut nsStyleUnit, union: &mut nsStyleUnion) {
+        unsafe { union.reset(unit) };
         match *self {
             LengthOrPercentageOrNone::Length(au) => {
                 *unit = nsStyleUnit::eStyleUnit_Coord;
@@ -232,7 +242,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentageOrNone {
                 *unit = nsStyleUnit::eStyleUnit_None;
                 unsafe { *union.mInt.as_mut() = 0; }
             },
-            LengthOrPercentageOrNone::Calc(_) => unimplemented!(),
+            LengthOrPercentageOrNone::Calc(calc) => unsafe { union.set_calc_value(unit, calc.into()) },
         };
     }
 
@@ -245,7 +255,7 @@ impl GeckoStyleCoordConvertible for LengthOrPercentageOrNone {
             nsStyleUnit::eStyleUnit_Percent
                 => Some(LengthOrPercentageOrNone::Percentage(unsafe { *union.mFloat.as_ref() })),
             nsStyleUnit::eStyleUnit_Calc
-                => unimplemented!(),
+                => Some(LengthOrPercentageOrNone::Calc(unsafe { union.get_calc().into()})),
             _ => None,
         }
     }