2 files changed, 6 insertions, 0 deletions
diff --git a/ext/dl/lib/dl/func.rb b/ext/dl/lib/dl/func.rb
index a2e6d40fbe..f0e1ca71ee 100644
--- a/ext/dl/lib/dl/func.rb
+++ b/ext/dl/lib/dl/func.rb
@@ -97,6 +97,10 @@ module DL
       end
     end
 
+    def bound?()
+      @cfunc.ptr != 0
+    end
+
     def bind_at_call(&block)
       bind(&block)
     end
diff --git a/ext/dl/lib/dl/value.rb b/ext/dl/lib/dl/value.rb
index aa7e0dd325..254e1921ce 100644
--- a/ext/dl/lib/dl/value.rb
+++ b/ext/dl/lib/dl/value.rb
@@ -61,6 +61,8 @@ module DL
           if( block )
             arg.bind_at_call(&block)
             funcs.push(arg)
+          elsif !arg.bound?
+            raise(RuntimeError, "block must be given.")
           end
           return arg.to_i
         when String