diff --git a/gtk/gtkcssprovider.c b/gtk/gtkcssprovider.c
index fd2696a32e..e93c894ef5 100644
--- a/gtk/gtkcssprovider.c
+++ b/gtk/gtkcssprovider.c
@@ -33,6 +33,7 @@
 #include "gtksymboliccolor.h"
 #include "gtkstyleprovider.h"
 #include "gtkstylecontextprivate.h"
+#include "gtkstylepropertiesprivate.h"
 #include "gtkbindings.h"
 #include "gtkmarshalers.h"
 #include "gtkprivate.h"
@@ -1130,20 +1131,15 @@ gtk_css_provider_get_style (GtkStyleProvider *provider,
 
       while (g_hash_table_iter_next (&iter, &key, &value))
         {
-          gchar *prop = key;
+          GParamSpec *pspec;
 
-          /* Properties starting with '-' may be both widget style properties
-           * or custom properties from the theming engine, so check whether
-           * the type is registered or not.
-           */
-          if (prop[0] == '-' &&
-              !gtk_style_properties_lookup_property (prop, NULL, NULL))
+          if (!gtk_style_properties_lookup_property (key, NULL, &pspec))
             continue;
 
-          gtk_style_properties_set_property (props,
-                                             key,
-                                             _gtk_css_selector_get_state_flags (info->selector),
-                                             value);
+          _gtk_style_properties_set_property_by_pspec (props,
+                                                       pspec,
+                                                       _gtk_css_selector_get_state_flags (info->selector),
+                                                       value);
         }
     }
 
diff --git a/gtk/gtkstyleproperties.c b/gtk/gtkstyleproperties.c
index aeabb95ff9..27e73929da 100644
--- a/gtk/gtkstyleproperties.c
+++ b/gtk/gtkstyleproperties.c
@@ -602,6 +602,60 @@ gtk_style_properties_lookup_color (GtkStyleProperties *props,
   return g_hash_table_lookup (priv->color_map, name);
 }
 
+void
+_gtk_style_properties_set_property_by_pspec (GtkStyleProperties *props,
+                                             GParamSpec         *pspec,
+                                             GtkStateFlags       state,
+                                             const GValue       *value)
+{
+  GtkStylePropertiesPrivate *priv;
+  PropertyData *prop;
+  GType value_type;
+  GValue *val;
+
+  value_type = G_VALUE_TYPE (value);
+
+  if (pspec->value_type == GDK_TYPE_RGBA ||
+      pspec->value_type == GDK_TYPE_COLOR)
+    {
+      /* Allow GtkSymbolicColor as well */
+      g_return_if_fail (value_type == GDK_TYPE_RGBA ||
+                        value_type == GDK_TYPE_COLOR ||
+                        value_type == GTK_TYPE_SYMBOLIC_COLOR);
+    }
+  else if (pspec->value_type == CAIRO_GOBJECT_TYPE_PATTERN)
+    {
+      /* Allow GtkGradient as a substitute */
+      g_return_if_fail (value_type == CAIRO_GOBJECT_TYPE_PATTERN ||
+                        value_type == GTK_TYPE_GRADIENT);
+    }
+  else
+    g_return_if_fail (pspec->value_type == value_type);
+
+  priv = props->priv;
+  prop = g_hash_table_lookup (priv->properties, pspec);
+
+  if (!prop)
+    {
+      prop = property_data_new ();
+      g_hash_table_insert (priv->properties, pspec, prop);
+    }
+
+  val = property_data_get_value (prop, state);
+
+  if (G_VALUE_TYPE (val) == value_type)
+    g_value_reset (val);
+  else
+    {
+      if (G_IS_VALUE (val))
+        g_value_unset (val);
+
+      g_value_init (val, value_type);
+    }
+
+  g_value_copy (value, val);
+}
+
 /**
  * gtk_style_properties_set_property:
  * @props: a #GtkStyleProperties
@@ -619,17 +673,12 @@ gtk_style_properties_set_property (GtkStyleProperties *props,
                                    GtkStateFlags       state,
                                    const GValue       *value)
 {
-  GtkStylePropertiesPrivate *priv;
   PropertyNode *node;
-  PropertyData *prop;
-  GType value_type;
-  GValue *val;
 
   g_return_if_fail (GTK_IS_STYLE_PROPERTIES (props));
   g_return_if_fail (property != NULL);
   g_return_if_fail (value != NULL);
 
-  value_type = G_VALUE_TYPE (value);
   node = property_node_lookup (property);
 
   if (!node)
@@ -638,45 +687,10 @@ gtk_style_properties_set_property (GtkStyleProperties *props,
       return;
     }
 
-  if (node->pspec->value_type == GDK_TYPE_RGBA ||
-      node->pspec->value_type == GDK_TYPE_COLOR)
-    {
-      /* Allow GtkSymbolicColor as well */
-      g_return_if_fail (value_type == GDK_TYPE_RGBA ||
-                        value_type == GDK_TYPE_COLOR ||
-                        value_type == GTK_TYPE_SYMBOLIC_COLOR);
-    }
-  else if (node->pspec->value_type == CAIRO_GOBJECT_TYPE_PATTERN)
-    {
-      /* Allow GtkGradient as a substitute */
-      g_return_if_fail (value_type == CAIRO_GOBJECT_TYPE_PATTERN ||
-                        value_type == GTK_TYPE_GRADIENT);
-    }
-  else
-    g_return_if_fail (node->pspec->value_type == value_type);
-
-  priv = props->priv;
-  prop = g_hash_table_lookup (priv->properties, node->pspec);
-
-  if (!prop)
-    {
-      prop = property_data_new ();
-      g_hash_table_insert (priv->properties, node->pspec, prop);
-    }
-
-  val = property_data_get_value (prop, state);
-
-  if (G_VALUE_TYPE (val) == value_type)
-    g_value_reset (val);
-  else
-    {
-      if (G_IS_VALUE (val))
-        g_value_unset (val);
-
-      g_value_init (val, value_type);
-    }
-
-  g_value_copy (value, val);
+  _gtk_style_properties_set_property_by_pspec (props,
+                                               node->pspec,
+                                               state,
+                                               value);
 }
 
 /**
diff --git a/gtk/gtkstylepropertiesprivate.h b/gtk/gtkstylepropertiesprivate.h
index 91dc72f6e9..f4cea2d44b 100644
--- a/gtk/gtkstylepropertiesprivate.h
+++ b/gtk/gtkstylepropertiesprivate.h
@@ -24,9 +24,14 @@
 
 G_BEGIN_DECLS
 
-const GValue * _gtk_style_properties_peek_property (GtkStyleProperties *props,
-                                                    const gchar        *prop_name,
-                                                    GtkStateFlags       state);
+const GValue * _gtk_style_properties_peek_property         (GtkStyleProperties *props,
+                                                            const gchar        *prop_name,
+                                                            GtkStateFlags       state);
+
+void           _gtk_style_properties_set_property_by_pspec (GtkStyleProperties *props,
+                                                            GParamSpec         *pspec,
+                                                            GtkStateFlags       state,
+                                                            const GValue       *value);
 
 G_END_DECLS