diff --git a/lldb/source/Expression/ClangUserExpression.cpp b/lldb/source/Expression/ClangUserExpression.cpp
index bd67bbdae628..dc93d8e69717 100644
--- a/lldb/source/Expression/ClangUserExpression.cpp
+++ b/lldb/source/Expression/ClangUserExpression.cpp
@@ -38,7 +38,7 @@ using namespace lldb_private;
 ClangUserExpression::ClangUserExpression (const char *expr,
                                           const char *expr_prefix) :
     m_expr_text(expr),
-    m_expr_prefix(expr_prefix),
+    m_expr_prefix(expr_prefix ? expr_prefix : ""),
     m_transformed_text(),
     m_jit_addr(LLDB_INVALID_ADDRESS),
     m_cplusplus(false),
@@ -483,4 +483,4 @@ ClangUserExpression::Evaluate (ExecutionContext &exe_ctx,
         result_valobj_sp.reset (new ValueObjectConstResult (error));
 
     return result_valobj_sp;
-}
\ No newline at end of file
+}