diff --git a/include/llvm/Support/DynamicLibrary.h b/include/llvm/Support/DynamicLibrary.h
index 2eb648d1091..a7d22212dbd 100644
--- a/include/llvm/Support/DynamicLibrary.h
+++ b/include/llvm/Support/DynamicLibrary.h
@@ -43,10 +43,11 @@ namespace sys {
     // Opaque data used to interface with OS-specific dynamic library handling.
     void *Data;
 
-    explicit DynamicLibrary(void *data = &Invalid) : Data(data) {}
   public:
+    explicit DynamicLibrary(void *data = &Invalid) : Data(data) {}
+
     /// Returns true if the object refers to a valid library.
-    bool isValid() { return Data != &Invalid; }
+    bool isValid() const { return Data != &Invalid; }
 
     /// Searches through the library for the symbol \p symbolName. If it is
     /// found, the address of that symbol is returned. If not, NULL is returned.