diff --git a/StringUtils.cpp b/StringUtils.cpp
index 9a98c88..a20a6ec 100644
--- a/StringUtils.cpp
+++ b/StringUtils.cpp
@@ -42,7 +42,7 @@ unsigned int CStringUtils::stringToPort(const std::string& s)
     unsigned int port = 0U;
     std::string ls = boost::trim_copy(s);
 
-    if(!ls.empty() && std::all_of(ls.begin(), ls.end(), [](char c){ return c > '0' && c < '9'; })) {
+    if(!ls.empty() && std::all_of(ls.begin(), ls.end(), [](char c){ return c >= '0' && c <= '9'; })) {
         auto portTemp = boost::lexical_cast<unsigned int>(ls);
         if(portTemp > 0U && portTemp <= 65535U)
             port = portTemp;
diff --git a/Tests/StringUtils/stringToPort.cpp b/Tests/StringUtils/stringToPort.cpp
index b4923ea..b3cc740 100644
--- a/Tests/StringUtils/stringToPort.cpp
+++ b/Tests/StringUtils/stringToPort.cpp
@@ -54,4 +54,33 @@ namespace StringUtilsTests
 
         EXPECT_EQ(port, 12345U);
     }
+
+    TEST_F(StringUtils_stringToPort, StringWithMixedAlphaAndNumbersreturns0)
+    {
+        unsigned int port = CStringUtils::stringToPort("123abc456");
+
+        EXPECT_EQ(port, 0U);
+    }
+
+    TEST_F(StringUtils_stringToPort, TooLargeValueReturns0)
+    {
+        unsigned int port = CStringUtils::stringToPort("999999");
+
+        EXPECT_EQ(port, 0U);
+    }
+
+
+    TEST_F(StringUtils_stringToPort, TestAllNumDigits)
+    {
+        EXPECT_EQ(CStringUtils::stringToPort("10"), 10U);
+        EXPECT_EQ(CStringUtils::stringToPort("11"), 11U);
+        EXPECT_EQ(CStringUtils::stringToPort("12"), 12U);
+        EXPECT_EQ(CStringUtils::stringToPort("13"), 13U);
+        EXPECT_EQ(CStringUtils::stringToPort("14"), 14U);
+        EXPECT_EQ(CStringUtils::stringToPort("15"), 15U);
+        EXPECT_EQ(CStringUtils::stringToPort("16"), 16U);
+        EXPECT_EQ(CStringUtils::stringToPort("17"), 17U);
+        EXPECT_EQ(CStringUtils::stringToPort("18"), 18U);
+        EXPECT_EQ(CStringUtils::stringToPort("19"), 19U);
+    }
 }
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