diff --git a/lib/sphinx/integration/extensions/thinking_sphinx/search.rb b/lib/sphinx/integration/extensions/thinking_sphinx/search.rb
index decc55d..92daab3 100644
--- a/lib/sphinx/integration/extensions/thinking_sphinx/search.rb
+++ b/lib/sphinx/integration/extensions/thinking_sphinx/search.rb
@@ -36,7 +36,8 @@ def with_composite_index_conditions
 
     composite_indexes.each do |name, fields|
       composite_conditions = fields.keys.each_with_object([]) do |field_name, memo|
-        memo << "(#{conditions.delete(field_name)})" if conditions.key?(field_name)
+        condition = conditions.delete(field_name) if conditions.key?(field_name)
+        memo << "(#{condition})" if condition.present?
       end
 
       next if composite_conditions.empty?
@@ -45,7 +46,7 @@ def with_composite_index_conditions
       old_composite_condition = conditions[name]
 
       conditions[name] =
-        if old_composite_condition
+        if old_composite_condition.present?
           "(#{old_composite_condition}) #{composite_conditions}"
         else
           composite_conditions
diff --git a/spec/sphinx/integration/extensions/thinking_sphinx/search_spec.rb b/spec/sphinx/integration/extensions/thinking_sphinx/search_spec.rb
index 16494c3..b98aba5 100644
--- a/spec/sphinx/integration/extensions/thinking_sphinx/search_spec.rb
+++ b/spec/sphinx/integration/extensions/thinking_sphinx/search_spec.rb
@@ -26,6 +26,60 @@
         expect(riddle_client).to have_received(:query)
           .with("@one_idx one @composite_idx (a_2 | a_1) (b_1 | b_2)", 'composite', any_args)
       end
+
+      context 'when condition contains empty string' do
+        it do
+          ModelWithDisk.search(conditions: {one_idx: 'one', b_idx: ' ', a_idx: "a_2 | a_1"}).to_a
+
+          expect(riddle_client).to have_received(:query)
+            .with("@one_idx one @composite_idx (a_2 | a_1)", 'composite', any_args)
+        end
+      end
+
+      context 'when condition contains nil' do
+        it do
+          ModelWithDisk.search(conditions: {one_idx: 'one', b_idx: nil, a_idx: "a_2 | a_1"}).to_a
+
+          expect(riddle_client).to have_received(:query)
+            .with("@one_idx one @composite_idx (a_2 | a_1)", 'composite', any_args)
+        end
+      end
+
+      context 'when old composite condition' do
+        it do
+          ModelWithDisk.search(conditions: {
+            one_idx: 'one',
+            composite_idx: 'z_1 | z_2', b_idx: 'b_1 | b_2', a_idx: "a_2 | a_1"
+          }).to_a
+
+          expect(riddle_client).to have_received(:query)
+            .with("@one_idx one @composite_idx (z_1 | z_2) (a_2 | a_1) (b_1 | b_2)", 'composite', any_args)
+        end
+      end
+
+      context 'when old composite condition is a empty string' do
+        it do
+          ModelWithDisk.search(conditions: {
+            one_idx: 'one',
+            composite_idx: ' ', b_idx: 'b_1 | b_2', a_idx: "a_2 | a_1"
+          }).to_a
+
+          expect(riddle_client).to have_received(:query)
+            .with("@one_idx one @composite_idx (a_2 | a_1) (b_1 | b_2)", 'composite', any_args)
+        end
+      end
+
+      context 'when old composite condition is a nil' do
+        it do
+          ModelWithDisk.search(conditions: {
+            one_idx: 'one',
+            composite_idx: nil, b_idx: 'b_1 | b_2', a_idx: "a_2 | a_1"
+          }).to_a
+
+          expect(riddle_client).to have_received(:query)
+            .with("@one_idx one @composite_idx (a_2 | a_1) (b_1 | b_2)", 'composite', any_args)
+        end
+      end
     end
   end
 end