diff --git a/CMakeLists.txt b/CMakeLists.txt
index 16bb2b3..1f6ab07 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,6 +60,7 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 include(GNUInstallDirs)
 
 if(WIN32)
+    set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
     set(LIBS_SYSTEM ws2_32)
 elseif(UNIX)
     set(LIBS_SYSTEM c stdc++)
diff --git a/buildtst.sh b/buildtst.sh
index c51171d..468a6d7 100755
--- a/buildtst.sh
+++ b/buildtst.sh
@@ -37,9 +37,9 @@ for COMPILER in $COMPILERS; do
             exit 1
         fi
 
-        printf "Running unit tests:\n"
+        printf "Running unit tests for %s:\n" "${COMPILER}"
         if ! ./test/unit/paho-mqttpp-test ; then
-            printf "\nUnit test failed for  %s\n" "${COMPILER}"
+            printf "\nUnit test failed for %s\n" "${COMPILER}"
             exit 3
         fi
 
diff --git a/src/message.cpp b/src/message.cpp
index 15d1046..cc48524 100644
--- a/src/message.cpp
+++ b/src/message.cpp
@@ -30,9 +30,6 @@ constexpr bool message::DFLT_RETAINED;
 
 const MQTTAsync_message message::DFLT_C_STRUCT = MQTTAsync_message_initializer;
 
-const string message::EMPTY_STR;
-const binary message::EMPTY_BIN;
-
 // --------------------------------------------------------------------------
 
 message::message() : msg_(DFLT_C_STRUCT)
diff --git a/src/mqtt/message.h b/src/mqtt/message.h
index 1c911c8..feb3b97 100644
--- a/src/mqtt/message.h
+++ b/src/mqtt/message.h
@@ -61,11 +61,6 @@ private:
 	/** Initializer for the C struct (from the C library) */
 	static const MQTTAsync_message DFLT_C_STRUCT;
 
-	/** An instance of an empty string (for performance)  */
-	static const string EMPTY_STR;
-	/** An instance of an empty binary (for performance)  */
-	static const binary EMPTY_BIN;
-
 	/** The underlying C message struct */
 	MQTTAsync_message msg_;
 	/** The topic that the message was (or should be) sent on. */
@@ -236,6 +231,7 @@ public:
 	 * @return The topic string for the message.
 	 */
 	const string& get_topic() const { 
+		static const string EMPTY_STR;
 		return topic_ ? topic_.str() : EMPTY_STR; 
 	}
 	/**
@@ -249,13 +245,15 @@ public:
 	/**
 	 * Gets the payload
 	 */
-	const binary& get_payload() const { 
+	const binary& get_payload() const {
+		static const binary EMPTY_BIN;
 		return payload_ ? payload_.str() : EMPTY_BIN; 
 	}
 	/**
 	 * Gets the payload as a string
 	 */
-	const string& get_payload_str() const { 
+	const string& get_payload_str() const {
+		static const string EMPTY_STR;
 		return payload_ ? payload_.str() : EMPTY_STR;
 	}
 	/**