diff --git a/Gemfile.lock b/Gemfile.lock
index cebcad8..6354ef9 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -4,7 +4,7 @@ PATH
     open_invoice (0.1.2)
       activesupport
       hashie (~> 3.6.0)
-      httparty (~> 0.18.0)
+      httparty (>= 0.18, < 0.22)
 
 GEM
   remote: https://rubygems.org/
@@ -21,14 +21,12 @@ GEM
     factory_bot (5.2.0)
       activesupport (>= 4.2.0)
     hashie (3.6.0)
-    httparty (0.18.1)
-      mime-types (~> 3.0)
+    httparty (0.21.0)
+      mini_mime (>= 1.0.0)
       multi_xml (>= 0.5.2)
     i18n (1.8.2)
       concurrent-ruby (~> 1.0)
-    mime-types (3.3.1)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2020.0512)
+    mini_mime (1.1.2)
     minitest (5.14.0)
     multi_xml (0.6.0)
     rake (10.5.0)
diff --git a/open_invoice.gemspec b/open_invoice.gemspec
index a75a2d3..e8e84c7 100644
--- a/open_invoice.gemspec
+++ b/open_invoice.gemspec
@@ -36,7 +36,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "httparty", "~> 0.18.0"
+  spec.add_runtime_dependency "httparty", ">= 0.18", "< 0.22"
   spec.add_runtime_dependency "hashie", "~> 3.6.0"
   spec.add_runtime_dependency "activesupport"