diff --git a/layout/style/crashtests/509569-1.html b/layout/style/crashtests/509569-1.html
new file mode 100644
index 000000000000..023c710401ee
--- /dev/null
+++ b/layout/style/crashtests/509569-1.html
@@ -0,0 +1,2 @@
+
+
diff --git a/layout/style/crashtests/crashtests.list b/layout/style/crashtests/crashtests.list
index 8d22e2346141..474d070cb1af 100644
--- a/layout/style/crashtests/crashtests.list
+++ b/layout/style/crashtests/crashtests.list
@@ -48,6 +48,7 @@ load 495269-2.html
load 498036-1.html
load 509155-1.html
load 509156-1.html
+load 509569-1.html
load 524252-1.html
load font-face-truncated-src.html
load 536789-1.html
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index a4f79a9bc355..cb9ce6b9ec59 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -2326,6 +2326,12 @@ nsRuleNode::AdjustLogicalBoxProp(nsStyleContext* aContext,
if (RTLlogical)
aValueRect.*(nsCSSRect::sides[aSide]) = aRTLLogicalValue;
}
+ } else if (aLTRLogicalValue.GetUnit() == eCSSUnit_Inherit ||
+ aRTLLogicalValue.GetUnit() == eCSSUnit_Inherit) {
+ // It actually is valid to store this in the ruletree, since
+ // LTRlogical and RTLlogical are both false, but doing that will
+ // trigger asserts. Silence those.
+ aCanStoreInRuleTree = PR_FALSE;
}
}