diff --git a/sysinstall/hooks.c b/sysinstall/hooks.c
index 4d74b316..3af2f307 100644
--- a/sysinstall/hooks.c
+++ b/sysinstall/hooks.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2016, 2017 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -51,12 +51,8 @@ void upgrade_finalize(const struct release* old_release,
 	(void) target_prefix;
 
 	// TODO: After releasing Sortix 1.1, remove this compatibility.
-	if ( old_release->version_major < 1 ||
-	     (old_release->version_major == 1 &&
-	      old_release->version_minor < 1) ||
-	     (old_release->version_major == 1 &&
-	      old_release->version_minor == 1 &&
-	      old_release->version_dev) )
+	if ( version_compare(old_release->version_major, old_release->version_minor,
+	                     old_release->version_dev, 1, 1, false) < 0 ) // < 1.1
 	{
 		char* random_seed_path;
 		if ( asprintf(&random_seed_path, "%sboot/random.seed", target_prefix) < 0 )
diff --git a/sysinstall/release.c b/sysinstall/release.c
index 3582db39..0c476d9a 100644
--- a/sysinstall/release.c
+++ b/sysinstall/release.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2015, 2016, 2017 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -27,6 +27,44 @@
 
 #include "release.h"
 
+int abi_compare(unsigned long a_major, unsigned long a_minor,
+                unsigned long b_major, unsigned long b_minor)
+{
+	if ( a_major < b_major )
+		return -1;
+	if ( a_major > b_major )
+		return 1;
+	if ( a_minor < b_minor )
+		return -1;
+	if ( a_minor > b_minor )
+		return 1;
+	return 0;
+}
+
+bool abi_compatible(unsigned long a_major, unsigned long a_minor,
+                    unsigned long b_major, unsigned long b_minor)
+{
+	return a_major == b_major && a_minor <= b_minor;
+}
+
+int version_compare(unsigned long a_major, unsigned long a_minor, bool a_dev,
+                    unsigned long b_major, unsigned long b_minor, bool b_dev)
+{
+	if ( a_major < b_major )
+		return -1;
+	if ( a_major > b_minor )
+		return 1;
+	if ( a_minor < b_minor )
+		return -1;
+	if ( a_minor > b_minor )
+		return 1;
+	if ( a_dev && !b_dev )
+		return -1;
+	if ( !a_dev && b_dev )
+		return 1;
+	return 0;
+}
+
 void release_free(struct release* release)
 {
 	free(release->pretty_name);
diff --git a/sysinstall/release.h b/sysinstall/release.h
index bc8f399c..54c62331 100644
--- a/sysinstall/release.h
+++ b/sysinstall/release.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2015, 2016, 2017 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -30,7 +30,15 @@ struct release
 	unsigned long abi_minor;
 };
 
+int abi_compare(unsigned long a_major, unsigned long a_minor,
+                unsigned long b_major, unsigned long b_minor);
+bool abi_compatible(unsigned long a_major, unsigned long a_minor,
+                    unsigned long b_major, unsigned long b_minor);
+int version_compare(unsigned long a_major, unsigned long a_minor, bool a_dev,
+                    unsigned long b_major, unsigned long b_minor, bool b_dev);
 void release_free(struct release* release);
+int release_compare_abi(const struct release* a, const struct release* b);
+int release_compare_version(const struct release* a, const struct release* b);
 bool os_release_load(struct release* release,
                      const char* path,
                      const char* errpath);
diff --git a/sysinstall/sysmerge.c b/sysinstall/sysmerge.c
index 49db562e..1eff27be 100644
--- a/sysinstall/sysmerge.c
+++ b/sysinstall/sysmerge.c
@@ -213,8 +213,9 @@ int main(int argc, char* argv[])
 	struct conf conf;
 	load_upgrade_conf(&conf, "/etc/upgrade.conf");
 
-	bool can_run_new_abi = new_release.abi_major == old_release.abi_major &&
-	                       new_release.abi_minor <= old_release.abi_minor;
+	bool can_run_new_abi =
+		abi_compatible(new_release.abi_major, new_release.abi_minor,
+		               old_release.abi_major, old_release.abi_minor);
 
 	bool header;
 	bool copy_files;
diff --git a/sysinstall/sysupgrade.c b/sysinstall/sysupgrade.c
index 9e462f59..d75b8e92 100644
--- a/sysinstall/sysupgrade.c
+++ b/sysinstall/sysupgrade.c
@@ -626,9 +626,8 @@ int main(void)
 		text("\n");
 	}
 
-	if ( new_release.abi_major < target_release->abi_major ||
-	     (target_release->abi_major == new_release.abi_major &&
-	      new_release.abi_minor < target_release->abi_minor) )
+	if ( abi_compare(new_release.abi_major, new_release.abi_minor,
+	                 target_release->abi_major, target_release->abi_minor) < 0 )
 	{
 		text("Warning: You are downgrading an existing installation to an "
 		     "release with an earlier ABI. This is not supported and there is "
@@ -646,8 +645,9 @@ int main(void)
 		text("\n");
 	}
 
-	bool can_run_old_abi = target_release->abi_major == new_release.abi_major &&
-	                       target_release->abi_minor <= new_release.abi_minor;
+	bool can_run_old_abi =
+		abi_compatible(target_release->abi_major, target_release->abi_minor,
+		               new_release.abi_major, new_release.abi_minor);
 
 	mountpoints = target->mountpoints;
 	mountpoints_used = target->mountpoints_used;