diff --git a/lib/bitcoin/script/script.rb b/lib/bitcoin/script/script.rb
index ea53e92..b25d454 100644
--- a/lib/bitcoin/script/script.rb
+++ b/lib/bitcoin/script/script.rb
@@ -55,7 +55,9 @@ def self.to_p2sh(script_hash)
 
     # generate p2sh script with this as a redeem script
     # @return [Script] P2SH script
+    # @raise [RuntimeError] If the script size exceeds 520 bytes
     def to_p2sh
+      raise RuntimeError, "P2SH redeem script must be 520 bytes or less." if size > Bitcoin::MAX_SCRIPT_ELEMENT_SIZE
       Script.to_p2sh(to_hash160)
     end
 
diff --git a/spec/bitcoin/script/script_spec.rb b/spec/bitcoin/script/script_spec.rb
index 72ac2d5..c64419d 100644
--- a/spec/bitcoin/script/script_spec.rb
+++ b/spec/bitcoin/script/script_spec.rb
@@ -139,6 +139,16 @@
         expect(subject[1].to_addr).to be nil
       end
     end
+
+    context 'invalid script length' do
+      it 'should raise error' do
+        boundary = Bitcoin::Script.new
+        520.times { boundary << OP_0 }
+        expect{ boundary.to_p2sh }.not_to raise_error
+        boundary << OP_0
+        expect{ boundary.to_p2sh }.to raise_error(RuntimeError)
+      end
+    end
   end
 
   describe 'p2wsh script' do