diff --git a/Gemfile.lock b/Gemfile.lock
index 48c7c6f..081a592 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -19,12 +19,16 @@ GEM
     commander (4.5.0)
       highline (~> 2.0.0)
     console (1.8.1)
-    gruff (0.7.0)
-      rmagick (~> 2.13, >= 2.13.4)
+    gruff (0.19.0)
+      histogram
+      rmagick (>= 4.2)
     highline (2.0.3)
+    histogram (0.2.4.1)
     nio4r (2.5.2)
     os (1.0.1)
-    rmagick (2.16.0)
+    pkg-config (1.5.5)
+    rmagick (5.3.0)
+      pkg-config (~> 1.4)
     timers (4.3.0)
 
 PLATFORMS