diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 346d4b38853..1b8a373afcc 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -1319,10 +1319,11 @@ fn static_assert() {
         let ident = v.ident.as_ref().map_or(&[] as &[_], |ident| ident.0.as_slice());
         self.gecko.${value.gecko}.mLineName.assign(ident);
         self.gecko.${value.gecko}.mHasSpan = v.is_span;
-        self.gecko.${value.gecko}.mInteger = v.line_num.map(|i| {
+        if let Some(integer) = v.line_num {
             // clamping the integer between a range
-            cmp::max(nsStyleGridLine_kMinLine, cmp::min(i.value(), nsStyleGridLine_kMaxLine))
-        }).unwrap_or(0);
+            self.gecko.${value.gecko}.mInteger = cmp::max(nsStyleGridLine_kMinLine,
+                cmp::min(integer.value(), nsStyleGridLine_kMaxLine));
+        }
     }
 
     pub fn copy_${value.name}_from(&mut self, other: &Self) {
diff --git a/components/style/values/generics/grid.rs b/components/style/values/generics/grid.rs
index 2b20269ecae..00049814482 100644
--- a/components/style/values/generics/grid.rs
+++ b/components/style/values/generics/grid.rs
@@ -119,9 +119,7 @@ impl Parse for GridLine {
                 if i.value() <= 0 {       // disallow negative integers for grid spans
                     return Err(StyleParseError::UnspecifiedError.into())
                 }
-            } else if grid_line.ident.is_some() {       // integer could be omitted
-                grid_line.line_num = Some(Integer::new(1));
-            } else {
+            } else if grid_line.ident.is_none() {       // integer could be omitted
                 return Err(StyleParseError::UnspecifiedError.into())
             }
         }