diff --git a/Environment-Test-Dockerfile b/Environment-Test-Dockerfile
index 70d370d..12f4d28 100644
--- a/Environment-Test-Dockerfile
+++ b/Environment-Test-Dockerfile
@@ -26,9 +26,6 @@ COPY ./src ./src
 COPY ./tests ./tests
 COPY ./CMakeLists.txt ./CMakeLists.txt
 
-# Do a fake copy to make sure it runs both stages
-COPY --from=alpine /alpine/build/test/CppSocketLibraryTests /ubuntu/CppSocketLibraryTests
-
 RUN ["cmake", "-B", "build", "."]
 
 WORKDIR /ubuntu/build
@@ -36,3 +33,6 @@ RUN ["make", "all"]
 
 WORKDIR /ubuntu/build/tests
 RUN ["./CppSocketLibraryTests"]
+
+# Do a fake copy to make sure it runs both stages
+COPY --from=alpine /alpine/build/tests/CppSocketLibraryTests /ubuntu/CppSocketLibraryTests
diff --git a/src/socket/UDPSocket.cpp b/src/socket/UDPSocket.cpp
index ecbd509..c4f3e43 100644
--- a/src/socket/UDPSocket.cpp
+++ b/src/socket/UDPSocket.cpp
@@ -225,9 +225,13 @@ namespace kt
 
     int UDPSocket::pollSocket(SOCKET socket, const long& timeout) const
 	{
+		if (kt::isInvalidSocket(socket))
+		{
+			return -1;
+		}
+
 		timeval timeOutVal{};
 		int res = kt::pollSocket(socket, timeout, &timeOutVal);
-
 		return res;
 	}