diff --git a/lib/opencage/geocoder.rb b/lib/opencage/geocoder.rb
index 9163937..ab0748e 100644
--- a/lib/opencage/geocoder.rb
+++ b/lib/opencage/geocoder.rb
@@ -13,6 +13,8 @@ def initialize(default_options = {})
     end
 
     def geocode(location, options = {})
+      raise_error("400 Not a valid location: `#{location.inspect}`") unless location.is_a?(String)
+
       request = Request.new(@api_key, location, options)
 
       begin
diff --git a/spec/open_cage/geocoder_spec.rb b/spec/open_cage/geocoder_spec.rb
index 0f3da56..c3daca5 100644
--- a/spec/open_cage/geocoder_spec.rb
+++ b/spec/open_cage/geocoder_spec.rb
@@ -83,7 +83,7 @@ def geo
       expect(geo.geocode('NOWHERE-INTERESTING')).to eql([])
     end
 
-    it 'raises and error when undefined query', :vcr do
+    it 'raises an error when undefined query', :vcr do
       expect do
         geo.geocode(nil)
       end.to raise_error(OpenCage::Error::InvalidRequest)
@@ -94,6 +94,12 @@ def geo
         geo.geocode('')
       end.to raise_error(OpenCage::Error::InvalidRequest)
     end
+
+    it 'raises a useful error when the query is not a string' do
+      expect do
+        geo.geocode({ query: 'NOT-A-STRING' }) # it's a hash
+      end.to raise_error(OpenCage::Error::InvalidRequest)
+    end
   end
 
   describe 'user agent' do