diff --git a/xs/src/semver/semver.c b/xs/src/semver/semver.c
index a193544036..527738644d 100644
--- a/xs/src/semver/semver.c
+++ b/xs/src/semver/semver.c
@@ -620,7 +620,7 @@ semver_numeric (semver_t *x) {
   return num;
 }
 
-static char *semver_strdup(const char *src) {
+char *semver_strdup(const char *src) {
   if (src == NULL) return NULL;
   size_t len = strlen(src) + 1;
   char *res = malloc(len);
diff --git a/xs/src/semver/semver.h b/xs/src/semver/semver.h
index 7251f51e3a..01a15fc43e 100644
--- a/xs/src/semver/semver.h
+++ b/xs/src/semver/semver.h
@@ -98,6 +98,9 @@ semver_is_valid (const char *s);
 int
 semver_clean (char *s);
 
+char *
+semver_strdup(const char *src);
+
 semver_t
 semver_copy(const semver_t *ver);
 
diff --git a/xs/src/slic3r/GUI/AppConfig.cpp b/xs/src/slic3r/GUI/AppConfig.cpp
index 100b2d69b3..965e8185d4 100644
--- a/xs/src/slic3r/GUI/AppConfig.cpp
+++ b/xs/src/slic3r/GUI/AppConfig.cpp
@@ -100,7 +100,13 @@ void AppConfig::load()
 
     // Figure out if datadir has legacy presets
     auto ini_ver = Semver::parse(get("version"));
-    m_legacy_datadir = ini_ver ? *ini_ver < Semver(1, 40, 0) : true;
+    m_legacy_datadir = false;
+    if (ini_ver) {
+        // Make 1.40.0 alphas compare well
+        ini_ver->set_metadata(boost::none);
+        ini_ver->set_prerelease(boost::none);
+        m_legacy_datadir = ini_ver < Semver(1, 40, 0);
+    }
 
     // Override missing or keys with their defaults.
     this->set_defaults();
diff --git a/xs/src/slic3r/Utils/Semver.hpp b/xs/src/slic3r/Utils/Semver.hpp
index bf3c78964c..87396d8124 100644
--- a/xs/src/slic3r/Utils/Semver.hpp
+++ b/xs/src/slic3r/Utils/Semver.hpp
@@ -22,14 +22,15 @@ public:
 	Semver() : ver(semver_zero()) {}
 
 	Semver(int major, int minor, int patch,
-		boost::optional<std::string> metadata = boost::none,
-		boost::optional<std::string> prerelease = boost::none)
+		boost::optional<const std::string&> metadata = boost::none,
+		boost::optional<const std::string&> prerelease = boost::none)
+		: ver(semver_zero())
 	{
 		ver.major = major;
 		ver.minor = minor;
 		ver.patch = patch;
-		ver.metadata = metadata ? std::strcpy(ver.metadata, metadata->c_str()) : nullptr;
-		ver.prerelease = prerelease ? std::strcpy(ver.prerelease, prerelease->c_str()) : nullptr;
+		set_metadata(metadata);
+		set_prerelease(prerelease);
 	}
 
 	static boost::optional<Semver> parse(const std::string &str)
@@ -82,6 +83,13 @@ public:
 	int 		patch() 	 const { return ver.patch; }
 	const char*	prerelease() const { return ver.prerelease; }
 	const char*	metadata() 	 const { return ver.metadata; }
+	
+	// Setters
+	void set_maj(int maj) { ver.major = maj; }
+	void set_min(int min) { ver.minor = min; }
+	void set_patch(int patch) { ver.patch = patch; }
+	void set_metadata(boost::optional<const std::string&> meta) { meta ? strdup(*meta) : nullptr; }
+	void set_prerelease(boost::optional<const std::string&> pre) { pre ? strdup(*pre) : nullptr; }
 
 	// Comparison
 	bool operator<(const Semver &b)  const { return ::semver_compare(ver, b.ver) == -1; }
@@ -124,6 +132,7 @@ private:
 	Semver(semver_t ver) : ver(ver) {}
 
 	static semver_t semver_zero() { return { 0, 0, 0, nullptr, nullptr }; }
+	static char * strdup(const std::string &str) { return ::semver_strdup(const_cast<char*>(str.c_str())); }
 };