Forgot that GCC doesn't recognize this flag

CMakeLists.txt

@@ -90,7 +90,7 @@ endif(WIN32)
 
 if(${CMAKE_CXX_COMPILER_ID} MATCHES "GNU")
     add_compile_options(-Wall -Wmaybe-uninitialized -Wuninitialized -Wunused -Wunused-local-typedefs
-                        -Wunused-parameter -Wunused-value -Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable -fno-exceptions -Wextra-semi)
+                        -Wunused-parameter -Wunused-value -Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable -fno-exceptions)
     add_compile_options(-Wno-reorder)  # disable this from -Wall, since it happens all over.
     add_compile_options(-fno-rtti)
 elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")