diff --git a/components/style/properties/helpers/animated_properties.mako.rs b/components/style/properties/helpers/animated_properties.mako.rs
index 8771093624a..29ccd1d2560 100644
--- a/components/style/properties/helpers/animated_properties.mako.rs
+++ b/components/style/properties/helpers/animated_properties.mako.rs
@@ -32,6 +32,7 @@ use selectors::parser::SelectorParseError;
 use smallvec::SmallVec;
 use std::borrow::Cow;
 use std::cmp;
+use std::fmt;
 #[cfg(feature = "gecko")] use hash::FnvHashMap;
 use style_traits::ParseError;
 use super::ComputedValues;
@@ -72,7 +73,7 @@ pub trait RepeatableListAnimatable: Animate {}
 /// NOTE: This includes the 'display' property since it is animatable from SMIL even though it is
 /// not animatable from CSS animations or Web Animations. CSS transitions also does not allow
 /// animating 'display', but for CSS transitions we have the separate TransitionProperty type.
-#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+#[derive(Clone, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum AnimatableLonghand {
@@ -84,6 +85,19 @@ pub enum AnimatableLonghand {
     % endfor
 }
 
+impl fmt::Debug for AnimatableLonghand {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let name = match *self {
+            % for property in data.longhands:
+                % if property.animatable:
+                    AnimatableLonghand::${property.camel_case} => "${property.camel_case}",
+                % endif
+            % endfor
+        };
+        formatter.write_str(name)
+    }
+}
+
 impl AnimatableLonghand {
     /// Returns true if this AnimatableLonghand is one of the discretely animatable properties.
     pub fn is_discrete(&self) -> bool {
@@ -204,7 +218,7 @@ pub fn nscsspropertyid_is_animatable(property: nsCSSPropertyID) -> bool {
 // beforehand.
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Debug, Eq, Hash, PartialEq, ToCss, ToComputedValue)]
+#[derive(Clone, Eq, Hash, PartialEq, ToCss, ToComputedValue)]
 pub enum TransitionProperty {
     /// All, any transitionable property changing should generate a transition.
     All,
@@ -219,6 +233,25 @@ pub enum TransitionProperty {
     Unsupported(CustomIdent)
 }
 
+impl fmt::Debug for TransitionProperty {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let name = match *self {
+            % for property in data.longhands + data.shorthands_except_all():
+                % if property.transitionable:
+                    TransitionProperty::${property.camel_case} => "${property.camel_case}",
+                % endif
+            % endfor
+            TransitionProperty::All => "All",
+            TransitionProperty::Unsupported(ref ident) => {
+                formatter.write_str("Unsupported(")?;
+                ident.fmt(formatter)?;
+                return formatter.write_str(")");
+            }
+        };
+        formatter.write_str(name)
+    }
+}
+
 impl TransitionProperty {
     /// Iterates over each longhand property.
     pub fn each<F: FnMut(&TransitionProperty) -> ()>(mut cb: F) {
@@ -316,19 +349,20 @@ impl<'a> From< &'a TransitionProperty> for nsCSSPropertyID {
 #[allow(non_upper_case_globals)]
 impl From<nsCSSPropertyID> for TransitionProperty {
     fn from(property: nsCSSPropertyID) -> TransitionProperty {
-        match property {
+        let unsupported = match property {
             % for prop in data.longhands + data.shorthands_except_all():
                 % if prop.transitionable:
                     ${helpers.to_nscsspropertyid(prop.ident)}
-                        => TransitionProperty::${prop.camel_case},
+                        => return TransitionProperty::${prop.camel_case},
                 % else:
                     ${helpers.to_nscsspropertyid(prop.ident)}
-                        => TransitionProperty::Unsupported(CustomIdent(Atom::from("${prop.ident}"))),
+                        => "${prop.ident}",
                 % endif
             % endfor
-            nsCSSPropertyID::eCSSPropertyExtra_all_properties => TransitionProperty::All,
+            nsCSSPropertyID::eCSSPropertyExtra_all_properties => return TransitionProperty::All,
             _ => panic!("Unconvertable nsCSSPropertyID: {:?}", property),
-        }
+        };
+        TransitionProperty::Unsupported(CustomIdent(Atom::from(unsupported)))
     }
 }
 
@@ -483,7 +517,7 @@ unsafe impl HasSimpleFFI for AnimationValueMap {}
 ///
 /// FIXME: We need to add a path for custom properties, but that's trivial after
 /// this (is a similar path to that of PropertyDeclaration).
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum AnimationValue {
     % for prop in data.longhands:
@@ -498,6 +532,19 @@ pub enum AnimationValue {
     % endfor
 }
 
+impl fmt::Debug for AnimationValue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let name = match *self {
+        % for prop in data.longhands:
+            % if prop.animatable:
+                AnimationValue::${prop.camel_case}(..) => "${prop.camel_case}",
+            % endif
+        % endfor
+        };
+        formatter.write_str(name)
+    }
+}
+
 impl AnimationValue {
     /// "Uncompute" this animation value in order to be used inside the CSS
     /// cascade.
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 4784d4c6482..7ecfcc5012a 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -446,7 +446,7 @@ bitflags! {
 }
 
 /// An identifier for a given longhand property.
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Clone, Copy, Eq, PartialEq)]
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum LonghandId {
@@ -456,6 +456,12 @@ pub enum LonghandId {
     % endfor
 }
 
+impl fmt::Debug for LonghandId {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str(self.name())
+    }
+}
+
 impl LonghandId {
     /// Get the name of this longhand property.
     pub fn name(&self) -> &'static str {
@@ -3597,7 +3603,7 @@ pub fn modify_border_style_for_inline_sides(style: &mut Arc<ComputedValues>,
 }
 
 /// An identifier for a given alias property.
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Clone, Copy, Eq, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum AliasId {
     % for i, property in enumerate(data.all_aliases()):
@@ -3606,6 +3612,17 @@ pub enum AliasId {
     % endfor
 }
 
+impl fmt::Debug for AliasId {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let name = match *self {
+            % for property in data.all_aliases():
+                AliasId::${property.camel_case} => "${property.camel_case}",
+            % endfor
+        };
+        formatter.write_str(name)
+    }
+}
+
 impl AliasId {
     /// Returns an nsCSSPropertyID.
     #[cfg(feature = "gecko")]