diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 08a87251d436..e0ae7fc8bb82 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -3521,6 +3521,7 @@ nsCSSFrameConstructor::ConstructFrameByDisplayType(nsIPresContext*          aPre
 
     // Use the 'display' property to choose a frame type
     switch (aDisplay->mDisplay) {
+    case NS_STYLE_DISPLAY_INLINE_BLOCK: // XXX temporary until really supported
     case NS_STYLE_DISPLAY_BLOCK:
     case NS_STYLE_DISPLAY_LIST_ITEM:
     case NS_STYLE_DISPLAY_RUN_IN:
diff --git a/layout/html/style/src/nsCSSFrameConstructor.cpp b/layout/html/style/src/nsCSSFrameConstructor.cpp
index 08a87251d436..e0ae7fc8bb82 100644
--- a/layout/html/style/src/nsCSSFrameConstructor.cpp
+++ b/layout/html/style/src/nsCSSFrameConstructor.cpp
@@ -3521,6 +3521,7 @@ nsCSSFrameConstructor::ConstructFrameByDisplayType(nsIPresContext*          aPre
 
     // Use the 'display' property to choose a frame type
     switch (aDisplay->mDisplay) {
+    case NS_STYLE_DISPLAY_INLINE_BLOCK: // XXX temporary until really supported
     case NS_STYLE_DISPLAY_BLOCK:
     case NS_STYLE_DISPLAY_LIST_ITEM:
     case NS_STYLE_DISPLAY_RUN_IN: