diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3d46e37..5278717 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,10 @@ project(swe1r-tools)
 
 set(CMAKE_C_STANDARD 11)
 
+if(CMAKE_COMPILER_IS_GNUCC)
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -pedantic -Wextra -Wno-unused-parameter -Werror")
+endif()
+
 add_definitions(-D__cdecl=)
 
 add_executable(decompress decompress.c)
diff --git a/decompress.c b/decompress.c
index 5d146b2..b79423b 100644
--- a/decompress.c
+++ b/decompress.c
@@ -7,7 +7,7 @@
 #define MAGIC(a1, a2, a3, a4) (((a1) << 24) | ((a2) << 16) | ((a3) << 8) | (a4))
 
 static inline uint32_t swap32(uint32_t v) {
-  return ((v & 0xFF0000 | (v >> 16)) >> 8) | (((v << 16) | v & 0xFF00) << 8);
+  return (((v & 0xFF0000) | (v >> 16)) >> 8) | (((v << 16) | (v & 0xFF00)) << 8);
 }
 
 //----- (0042D520) --------------------------------------------------------