diff --git a/Foundation/src/Process_WIN32U.cpp b/Foundation/src/Process_WIN32U.cpp
index d26ebd04a..2a553fd90 100644
--- a/Foundation/src/Process_WIN32U.cpp
+++ b/Foundation/src/Process_WIN32U.cpp
@@ -176,14 +176,14 @@ bool ProcessImpl::mustEscapeArg(const std::string& arg)
 			inQuotes = !inQuotes;
 		}
 	}
-	return result && !inQuotes;
+	return result || inQuotes;
 }
 
 
 // Based on code from https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/
 std::string ProcessImpl::escapeArg(const std::string& arg)
 {
-	if (mostEscapeArg(arg))
+	if (mustEscapeArg(arg))
 	{
 		std::string quotedArg("\"");
 		for (std::string::const_iterator it = arg.begin(); ; ++it)
@@ -214,10 +214,7 @@ std::string ProcessImpl::escapeArg(const std::string& arg)
 		quotedArg.push_back('"');
 		return quotedArg;
 	}
-	else
-	{
-		return arg;
-	}
+	else return arg;
 }
 
 
diff --git a/Foundation/testsuite/src/ProcessTest.cpp b/Foundation/testsuite/src/ProcessTest.cpp
index 1681a774f..cac8718e8 100644
--- a/Foundation/testsuite/src/ProcessTest.cpp
+++ b/Foundation/testsuite/src/ProcessTest.cpp
@@ -16,6 +16,7 @@
 #include "Poco/PipeStream.h"
 
 
+using namespace std::string_literals;
 using Poco::Process;
 using Poco::ProcessHandle;
 using Poco::Pipe;
@@ -33,6 +34,24 @@ ProcessTest::~ProcessTest()
 }
 
 
+void ProcessTest::testEscapeArgs()
+{
+#if defined(_WIN32)
+	assertTrue (Poco::ProcessImpl::mustEscapeArg("a b"));
+	assertFalse (Poco::ProcessImpl::mustEscapeArg("abc"));
+	assertFalse (Poco::ProcessImpl::mustEscapeArg("\"a b \""));
+	assertFalse (Poco::ProcessImpl::mustEscapeArg("\"abc\""));
+	assertTrue (Poco::ProcessImpl::mustEscapeArg("\"a b "));
+	assertFalse (Poco::ProcessImpl::mustEscapeArg("/arg=\"a b c\""));
+
+	assertEquals ("abc"s, Poco::ProcessImpl::escapeArg("abc"));
+	assertEquals ("\"a b c\""s, Poco::ProcessImpl::escapeArg("a b c"));
+	assertEquals ("\"a b \\\" c\""s, Poco::ProcessImpl::escapeArg("a b \" c"));
+	assertEquals ("/arg=\"a b c\""s, Poco::ProcessImpl::escapeArg("/arg=\"a b c\""));
+#endif
+}
+
+
 void ProcessTest::testLaunch()
 {
 	std::string name("TestApp");
@@ -253,6 +272,7 @@ CppUnit::Test* ProcessTest::suite()
 {
 	CppUnit::TestSuite* pSuite = new CppUnit::TestSuite("ProcessTest");
 
+	CppUnit_addTest(pSuite, ProcessTest, testEscapeArgs);
 	CppUnit_addTest(pSuite, ProcessTest, testLaunch);
 	CppUnit_addTest(pSuite, ProcessTest, testLaunchRedirectIn);
 	CppUnit_addTest(pSuite, ProcessTest, testLaunchRedirectOut);
diff --git a/Foundation/testsuite/src/ProcessTest.h b/Foundation/testsuite/src/ProcessTest.h
index 130f4ad22..a99a77645 100644
--- a/Foundation/testsuite/src/ProcessTest.h
+++ b/Foundation/testsuite/src/ProcessTest.h
@@ -24,6 +24,7 @@ public:
 	ProcessTest(const std::string& name);
 	~ProcessTest();
 
+	void testEscapeArgs();
 	void testLaunch();
 	void testLaunchRedirectIn();
 	void testLaunchRedirectOut();