diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index f26b8ed..df9fdeb 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -3405,7 +3405,7 @@
 }
 
 DeclContextList NamespaceSpecifierSet::BuildContextChain(DeclContext *Start) {
-  assert(Start && "Bulding a context chain from a null context");
+  assert(Start && "Building a context chain from a null context");
   DeclContextList Chain;
   for (DeclContext *DC = Start->getPrimaryContext(); DC != NULL;
        DC = DC->getLookupParent()) {