diff --git a/lib/win32/certstore/mixin/assertions.rb b/lib/win32/certstore/mixin/assertions.rb
index fcfba97..5aa4af4 100644
--- a/lib/win32/certstore/mixin/assertions.rb
+++ b/lib/win32/certstore/mixin/assertions.rb
@@ -22,8 +22,8 @@ module Mixin
       module Assertions
         # Validate certificate store name
         def validate_store(store_name)
-          unless valid_store_name.include?(store_name.to_s.upcase)
-            raise ArgumentError, "Invalid Certificate Store."
+          if store_name.to_s.strip.empty?
+            raise ArgumentError, "Empty Certificate Store."
           end
         end
 
diff --git a/spec/win32/unit/certstore_spec.rb b/spec/win32/unit/certstore_spec.rb
index 7aa0f7d..649a7ae 100644
--- a/spec/win32/unit/certstore_spec.rb
+++ b/spec/win32/unit/certstore_spec.rb
@@ -29,21 +29,21 @@
     context "When passing empty certificate store name" do
       let(:store_name) { "" }
       it "raises ArgumentError" do
-        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Invalid Certificate Store.")
+        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Empty Certificate Store.")
       end
     end
 
     context "When passing invalid certificate store name" do
       let(:store_name) { "Chef" }
       it "raises ArgumentError" do
-        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Invalid Certificate Store.")
+        expect { certstore.open(store_name) }.not_to raise_error(ArgumentError, "Empty Certificate Store.")
       end
     end
 
     context "When passing nil certificate store name" do
       let(:store_name) { nil }
       it "raises ArgumentError" do
-        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Invalid Certificate Store.")
+        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Empty Certificate Store.")
       end
     end
 
@@ -102,7 +102,7 @@
     context "When passing empty certificate store name" do
       let(:store_name) { "" }
       it "raises ArgumentError" do
-        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Invalid Certificate Store.")
+        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Empty Certificate Store.")
       end
     end
 
@@ -190,7 +190,7 @@
     context "When passing empty certificate store name" do
       let(:store_name) { "" }
       it "raises ArgumentError" do
-        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Invalid Certificate Store.")
+        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Empty Certificate Store.")
       end
     end
 
@@ -272,7 +272,7 @@
     context "When passing empty certificate store name" do
       let(:store_name) { "" }
       it "raises ArgumentError" do
-        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Invalid Certificate Store.")
+        expect { certstore.open(store_name) }.to raise_error(ArgumentError, "Empty Certificate Store.")
       end
     end
 
diff --git a/spec/win32/unit/store/assertions_spec.rb b/spec/win32/unit/store/assertions_spec.rb
index f56c21a..e5fe4e4 100644
--- a/spec/win32/unit/store/assertions_spec.rb
+++ b/spec/win32/unit/store/assertions_spec.rb
@@ -31,21 +31,21 @@ class Store
     context "When passing empty certificate store name" do
       let(:store_name) { "" }
       it "raises ArgumentError" do
-        expect { certstore.validate_store(store_name) }.to raise_error("Invalid Certificate Store.")
+        expect { certstore.validate_store(store_name) }.to raise_error("Empty Certificate Store.")
       end
     end
 
     context "When passing invalid certificate store name" do
       let(:store_name) { "Chef" }
       it "raises ArgumentError" do
-        expect { certstore.validate_store(store_name) }.to raise_error("Invalid Certificate Store.")
+        expect { certstore.validate_store(store_name) }.to raise_error("Empty Certificate Store.")
       end
     end
 
     context "When passing empty certificate store name" do
       let(:store_name) { nil }
       it "raises ArgumentError" do
-        expect { certstore.validate_store(store_name) }.to raise_error("Invalid Certificate Store.")
+        expect { certstore.validate_store(store_name) }.to raise_error("Empty Certificate Store.")
       end
     end