diff --git a/.vimrc b/.vimrc
index e3e881a..39419eb 100644
--- a/.vimrc
+++ b/.vimrc
@@ -5,5 +5,5 @@ nnoremap <F4> :ter ++close env LD_LIBRARY_PATH=$LD_LIBRARY_PATH:./ ./_build/debu
 
 packadd termdebug
 let g:termdebug_wide = 1
-let g:syntastic_c_include_dirs = [ '_build/debug', '/usr/include/SDL2', 'steamworks_c_wrapper/src', 'physfs-3.0/src', 'bh_random/src' ]
+let g:syntastic_c_include_dirs = [ '_build/debug', '/usr/include/SDL2', 'steamworks_c_wrapper/src', 'physfs-3.0/src', 'bh_random/src', 'checksum/src' ]
 let g:syntastic_cpp_include_dirs = [ 'steamworks_c_wrapper/sdk/public/steam', 'bh_random/src' ]
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 61ad268..2b6e8d1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,6 +40,7 @@ if (STEAM)
 	add_subdirectory(steamworks_c_wrapper)
 endif()
 add_subdirectory(bh_random)
+add_subdirectory(checksum)
 
 if ("${CMAKE_C_COMPILER_ID}" STREQUAL "Clang")
 	set(CLANG 1)
@@ -130,6 +131,7 @@ include_directories(
 	${LUA_INCLUDE_DIR}
 	sqlite3
 	bh_random/src
+	checksum/src
 	)
 
 if (CMOCKA_FOUND)
@@ -249,6 +251,7 @@ target_link_libraries(breakhack
 	${LUA_LIBRARIES}
 	${PHYSFS_LIBRARY}
 	bh_random
+	checksum
 	)
 
 if (STEAM)
diff --git a/checksum/CMakeLists.txt b/checksum/CMakeLists.txt
new file mode 100644
index 0000000..6831492
--- /dev/null
+++ b/checksum/CMakeLists.txt
@@ -0,0 +1,33 @@
+cmake_minimum_required(VERSION 3.1)
+project(checksum C)
+
+if (NOT CMAKE_BUILD_TYPE)
+	set(CMAKE_BUILD_TYPE Release)
+endif ()
+
+
+add_executable(checksumtool
+	src/checksum
+	)
+target_compile_definitions(checksumtool PUBLIC EXECUTABLE=1)
+
+add_library(checksum
+	src/checksum
+	)
+
+IF ( MSVC )
+    MESSAGE ( STATUS "Setting MSVC MT switches")
+		string (REPLACE
+			"/MDd"
+			"/MTd"
+			CMAKE_C_FLAGS_DEBUG
+			${CMAKE_C_FLAGS_DEBUG}
+    )
+		string (REPLACE
+			"/MDd"
+			"/MTd"
+			CMAKE_C_FLAGS_RELEASE
+			${CMAKE_C_FLAGS_RELEASE}
+    )
+endif ()
+
diff --git a/checksum/src/checksum.c b/checksum/src/checksum.c
new file mode 100644
index 0000000..1248b13
--- /dev/null
+++ b/checksum/src/checksum.c
@@ -0,0 +1,61 @@
+/*
+**  CHECKSUM.C - Compute the checksum of a file
+**
+**  public somain demo by Bob Stout
+*/
+
+#include <stdlib.h>
+#include "checksum.h"
+
+unsigned
+checksum(void *buffer, size_t len, unsigned int seed)
+{
+      unsigned char *buf = (unsigned char *)buffer;
+      size_t i;
+
+      for (i = 0; i < len; ++i)
+            seed += (unsigned int)(*buf++);
+      return seed;
+}
+
+unsigned
+checksum_fp(FILE *fp)
+{
+      unsigned int seed = 0;
+      char buf[4096];
+
+      size_t len;
+      do {
+	      len = fread(buf, sizeof(char), sizeof(buf), fp);
+	      seed = checksum(buf, len, seed);
+      } while (len > 0);
+
+      return seed;
+}
+
+#ifdef EXECUTABLE
+#include <stdio.h>
+
+int main(int argc, char *argv[])
+{
+      FILE *fp;
+      const char *file;
+
+      if (argc < 2) {
+	      printf("You need to provide an input file\n");
+	      printf("Example: %s <file>", argv[0]);
+      }
+      file = argv[1];
+
+      if (NULL == (fp = fopen(file, "rb")))
+      {
+            printf("Unable to open %s for reading\n", file);
+            return -1;
+      }
+
+      printf("The checksum of %s is %#x\n", file, checksum_fp(fp));
+
+      return 0;
+}
+
+#endif
diff --git a/checksum/src/checksum.h b/checksum/src/checksum.h
new file mode 100644
index 0000000..cb10fd8
--- /dev/null
+++ b/checksum/src/checksum.h
@@ -0,0 +1,27 @@
+/*
+ * BreakHack - A dungeone crawler RPG
+ * Copyright (C) 2018  Linus Probert <linus.probert@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdio.h>
+
+unsigned
+checksum(void *buffer, size_t len, unsigned int seed);
+
+unsigned
+checksum_fp(FILE *fp);
diff --git a/src/defines.h b/src/defines.h
index b3dd6ff..8fa82c7 100644
--- a/src/defines.h
+++ b/src/defines.h
@@ -22,6 +22,10 @@
 #include <stdint.h>
 #include "config.h"
 
+/* Checksums */
+#define SO_LIBSTEAM_CHECKSUM 	0x19ba253
+#define DLL_LIBSTEAM_CHECKSUM 	0x19ba253
+
 /* Room/Map dimensions */
 #define MAP_ROOM_WIDTH		16
 #define MAP_ROOM_HEIGHT		12
diff --git a/src/main.c b/src/main.c
index 02e9230..da8d6f6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -57,6 +57,7 @@
 #include "time.h"
 #include "sprite_util.h"
 #include "event.h"
+#include "checksum.h"
 
 #ifdef STEAM_BUILD
 #include "steam/steamworks_api_wrapper.h"
@@ -1361,10 +1362,39 @@ void close(void)
 	SDL_Quit();
 }
 
+static void
+validate_lib_checksum(void)
+{
+	FILE *fp;
+#ifdef WIN32
+	const char *file = "./libsteam_api.dll";
+	unsigned int expected = DLL_LIBSTEAM_CHECKSUM;
+#else
+	const char *file = "./libsteam_api.so";
+	unsigned int expected = SO_LIBSTEAM_CHECKSUM;
+#endif
+
+	if (NULL == (fp = fopen(file, "rb")))
+	{
+		fatal("Unable to open %s for reading\n", file);
+	}
+	unsigned calculated = checksum_fp(fp);	
+
+	if (calculated != expected) {
+		fatal("Checksum validation failiure: %#x != %#x", calculated, expected);
+	} else {
+		info("Checksum validated: %#x", calculated);
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	UNUSED(argc);
 
+#ifdef STEAM_BUILD
+	validate_lib_checksum();
+#endif // STEAM_BUILD
+
 	PHYSFS_init(argv[0]);
 #ifndef DEBUG
 	PHYSFS_mount("assets.pack", NULL, 0);