diff --git a/content/html/style/src/nsDOMCSSDeclaration.cpp b/content/html/style/src/nsDOMCSSDeclaration.cpp
index f3357f90cf7c..772bde56dd85 100644
--- a/content/html/style/src/nsDOMCSSDeclaration.cpp
+++ b/content/html/style/src/nsDOMCSSDeclaration.cpp
@@ -179,7 +179,7 @@ nsDOMCSSDeclaration::GetPropertyPriority(const nsAString& aPropertyName,
   }
 
   if ((NS_OK == result) && isImportant) {
-    aReturn.Assign(NS_LITERAL_STRING("!important"));    
+    aReturn.Assign(NS_LITERAL_STRING("important"));    
   }
   else {
     aReturn.SetLength(0);
@@ -201,7 +201,7 @@ nsDOMCSSDeclaration::SetProperty(const nsAString& aPropertyName,
   }
 
   return ParseDeclaration(aPropertyName + NS_LITERAL_STRING(":") +
-                          aValue + aPriority,
+                          aValue + NS_LITERAL_STRING("!") + aPriority,
                           PR_TRUE, PR_FALSE);
 }
 
diff --git a/extensions/inspector/resources/content/viewers/styleRules/styleRules.js b/extensions/inspector/resources/content/viewers/styleRules/styleRules.js
index a06270cb3af7..ff84552a0be5 100644
--- a/extensions/inspector/resources/content/viewers/styleRules/styleRules.js
+++ b/extensions/inspector/resources/content/viewers/styleRules/styleRules.js
@@ -248,7 +248,7 @@ StyleRulesViewer.prototype =
     var propval = style.getPropertyValue(propname);
 
     var priority = style.getPropertyPriority(propname);
-    priority = priority == "!important" ? "!blah" : "!important";
+    priority = priority == "important" ? "" : "important";
 
     style.removeProperty(propname);
     style.setProperty(propname, propval, priority);
@@ -396,7 +396,7 @@ function(aRow, aColId, aProperties)
 {
   if (aColId == "olcPropPriority") {
     var prop = this.mDec.item(aRow);
-    if (this.mDec.getPropertyPriority(prop) == "!important") {
+    if (this.mDec.getPropertyPriority(prop) == "important") {
       aProperties.AppendElement(this.createAtom("important"));
     }
   }
diff --git a/layout/style/nsDOMCSSDeclaration.cpp b/layout/style/nsDOMCSSDeclaration.cpp
index f3357f90cf7c..772bde56dd85 100644
--- a/layout/style/nsDOMCSSDeclaration.cpp
+++ b/layout/style/nsDOMCSSDeclaration.cpp
@@ -179,7 +179,7 @@ nsDOMCSSDeclaration::GetPropertyPriority(const nsAString& aPropertyName,
   }
 
   if ((NS_OK == result) && isImportant) {
-    aReturn.Assign(NS_LITERAL_STRING("!important"));    
+    aReturn.Assign(NS_LITERAL_STRING("important"));    
   }
   else {
     aReturn.SetLength(0);
@@ -201,7 +201,7 @@ nsDOMCSSDeclaration::SetProperty(const nsAString& aPropertyName,
   }
 
   return ParseDeclaration(aPropertyName + NS_LITERAL_STRING(":") +
-                          aValue + aPriority,
+                          aValue + NS_LITERAL_STRING("!") + aPriority,
                           PR_TRUE, PR_FALSE);
 }