diff --git a/lib/vmpooler/api/v1.rb b/lib/vmpooler/api/v1.rb
index dfba6fb..8fdc590 100644
--- a/lib/vmpooler/api/v1.rb
+++ b/lib/vmpooler/api/v1.rb
@@ -499,6 +499,8 @@ module Vmpooler
                     arg[tag] = arg[tag].match(filter).captures.join if arg[tag].match(filter)
                   end
 
+                  next if arg[tag].nil? or arg[tag].empty?
+
                   backend.hset('vmpooler__vm__' + params[:hostname], 'tag:' + tag, arg[tag])
                   backend.hset('vmpooler__tag__' + Date.today.to_s, params[:hostname] + ':' + tag, arg[tag])
                 end
diff --git a/spec/vmpooler/api/v1_spec.rb b/spec/vmpooler/api/v1_spec.rb
index 788bc24..7c17b82 100644
--- a/spec/vmpooler/api/v1_spec.rb
+++ b/spec/vmpooler/api/v1_spec.rb
@@ -323,6 +323,15 @@ describe Vmpooler::API::V1 do
           expect(last_response.status).to eq(200)
         end
 
+        it 'skips empty tags' do
+          put "#{prefix}/vm/testhost", '{"tags":{"tested_by":""}}'
+
+          expect(last_response).to be_ok
+          expect(last_response.header['Content-Type']).to eq('application/json')
+          expect(last_response.body).to eq(JSON.pretty_generate({'ok' => true}))
+          expect(last_response.status).to eq(200)
+        end
+
         it 'does not set tags if request body format is invalid' do
           put "#{prefix}/vm/testhost", '{"tags":{"tested"}}'