diff --git a/.rubocop.yml b/.rubocop.yml
index 684e8e6d..e697bf42 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -12,7 +12,7 @@ Metrics/CyclomaticComplexity:
   Max: 10
 
 Metrics/MethodLength:
-  Max: 20
+  Max: 25
 
 Metrics/PerceivedComplexity:
   Max: 8
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
index 41f1a2dd..621d667c 100644
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -2,6 +2,7 @@
 
 ## unreleased
 
+* Fail if version of bin can't be detected [#39](https://github.com/toy/image_optim/issues/39) [@toy](https://github.com/toy)
 * Check path in `XXX_BIN` to exist, be a file and be executable [@toy](https://github.com/toy)
 
 ## v0.16.0 (2014-09-12)
diff --git a/lib/image_optim/bin_resolver.rb b/lib/image_optim/bin_resolver.rb
index cdcf0b27..cad5622e 100644
--- a/lib/image_optim/bin_resolver.rb
+++ b/lib/image_optim/bin_resolver.rb
@@ -29,6 +29,8 @@ def to_s
       end
 
       def check!
+        fail BadVersion, "didn't get version of `#{self}`" unless version
+
         is = ComparableCondition.is
         case name
         when :pngcrush