diff --git a/gtk/gtkcssnumbervalue.c b/gtk/gtkcssnumbervalue.c
index c929f1d274..479662c22b 100644
--- a/gtk/gtkcssnumbervalue.c
+++ b/gtk/gtkcssnumbervalue.c
@@ -19,6 +19,7 @@
 
 #include "gtkcssnumbervalueprivate.h"
 
+#include "gtkcssenumvalueprivate.h"
 #include "gtkstylepropertyprivate.h"
 
 struct _GtkCssValue {
@@ -38,6 +39,40 @@ gtk_css_value_number_compute (GtkCssValue     *number,
                               guint            property_id,
                               GtkStyleContext *context)
 {
+  GtkBorderStyle border_style;
+
+  /* I don't like this special case being here in this generic code path, but no idea where else to put it. */
+  switch (property_id)
+    {
+      case GTK_CSS_PROPERTY_BORDER_TOP_WIDTH:
+        border_style = _gtk_css_border_style_value_get (_gtk_style_context_peek_property (context, GTK_CSS_PROPERTY_BORDER_TOP_STYLE));
+        if (border_style == GTK_BORDER_STYLE_NONE || border_style == GTK_BORDER_STYLE_HIDDEN)
+          return _gtk_css_number_value_new (0, GTK_CSS_PX);
+        break;
+      case GTK_CSS_PROPERTY_BORDER_RIGHT_WIDTH:
+        border_style = _gtk_css_border_style_value_get (_gtk_style_context_peek_property (context, GTK_CSS_PROPERTY_BORDER_RIGHT_STYLE));
+        if (border_style == GTK_BORDER_STYLE_NONE || border_style == GTK_BORDER_STYLE_HIDDEN)
+          return _gtk_css_number_value_new (0, GTK_CSS_PX);
+        break;
+      case GTK_CSS_PROPERTY_BORDER_BOTTOM_WIDTH:
+        border_style = _gtk_css_border_style_value_get (_gtk_style_context_peek_property (context, GTK_CSS_PROPERTY_BORDER_BOTTOM_STYLE));
+        if (border_style == GTK_BORDER_STYLE_NONE || border_style == GTK_BORDER_STYLE_HIDDEN)
+          return _gtk_css_number_value_new (0, GTK_CSS_PX);
+        break;
+      case GTK_CSS_PROPERTY_BORDER_LEFT_WIDTH:
+        border_style = _gtk_css_border_style_value_get (_gtk_style_context_peek_property (context, GTK_CSS_PROPERTY_BORDER_LEFT_STYLE));
+        if (border_style == GTK_BORDER_STYLE_NONE || border_style == GTK_BORDER_STYLE_HIDDEN)
+          return _gtk_css_number_value_new (0, GTK_CSS_PX);
+        break;
+      case GTK_CSS_PROPERTY_OUTLINE_WIDTH:
+        border_style = _gtk_css_border_style_value_get (_gtk_style_context_peek_property (context, GTK_CSS_PROPERTY_OUTLINE_STYLE));
+        if (border_style == GTK_BORDER_STYLE_NONE || border_style == GTK_BORDER_STYLE_HIDDEN)
+          return _gtk_css_number_value_new (0, GTK_CSS_PX);
+        break;
+      default:
+        break;
+    }
+
   switch (number->unit)
     {
     default:
diff --git a/gtk/gtkcssstylepropertyimpl.c b/gtk/gtkcssstylepropertyimpl.c
index bf7fa993f8..840e3aec87 100644
--- a/gtk/gtkcssstylepropertyimpl.c
+++ b/gtk/gtkcssstylepropertyimpl.c
@@ -831,18 +831,7 @@ compute_border_width (GtkCssStyleProperty    *property,
                       GtkStyleContext        *context,
                       GtkCssValue            *specified)
 {
-  GtkBorderStyle border_style;
-  
-  /* The -1 is magic that is only true because we register the style
-   * properties directly after the width properties.
-   */
-  border_style = _gtk_css_border_style_value_get (_gtk_style_context_peek_property (context, _gtk_css_style_property_get_id (property) - 1));
-
-  if (border_style == GTK_BORDER_STYLE_NONE ||
-      border_style == GTK_BORDER_STYLE_HIDDEN)
-    return _gtk_css_number_value_new (0, GTK_CSS_PX);
-  else
-    return _gtk_css_value_compute (specified, _gtk_css_style_property_get_id (property), context);
+  return _gtk_css_value_compute (specified, _gtk_css_style_property_get_id (property), context);
 }
 
 static GtkCssValue *
@@ -1107,8 +1096,8 @@ _gtk_css_style_property_init_properties (void)
                                           query_length_as_int,
                                           assign_length_from_int,
                                           _gtk_css_number_value_new (0.0, GTK_CSS_PX));
-  /* IMPORTANT: compute_border_width() requires that the border-width
-   * properties be immeditaly followed by the border-style properties
+  /* IMPORTANT: the border-width properties must come after border-style properties,
+   * they depend on them for their value computation.
    */
   gtk_css_style_property_register        ("border-top-style",
                                           GTK_CSS_PROPERTY_BORDER_TOP_STYLE,