diff --git a/src/crc32/crc32_neon.cpp b/src/crc32/crc32_neon.cpp
index c0131a5..42158c4 100644
--- a/src/crc32/crc32_neon.cpp
+++ b/src/crc32/crc32_neon.cpp
@@ -31,32 +31,36 @@ namespace wren::detail {
 	//King_DuckZ - adapted from
 	//https://github.com/rurban/smhasher/blob/master/sse2neon.h
 	namespace {
-		[[gnu::always_inline]]
-		std::uint32_t neon_crc32cb(std::uint32_t crc, std::uint8_t v) {
+		[[gnu::always_inline]] [[gnu::const]]
+		inline std::uint32_t neon_crc32cb(std::uint32_t crc, std::uint8_t v) {
 			__asm__ __volatile__("crc32cb %w[c], %w[c], %w[v]\n\t"
 								 : [c] "+r"(crc)
 								 : [v] "r"(v));
+			return crc;
 		}
 
-		[[gnu::always_inline]]
-		std::uint32_t neon_crc32ch (std::uint32_t crc, std::uint16_t v) {
+		[[gnu::always_inline]] [[gnu::const]]
+		inline std::uint32_t neon_crc32ch (std::uint32_t crc, std::uint16_t v) {
 			__asm__ __volatile__("crc32ch %w[c], %w[c], %w[v]\n\t"
 								 : [c] "+r"(crc)
 								 : [v] "r"(v));
+			return crc;
 		}
 
-		[[gnu::always_inline]]
-		std::uint32_t neon_crc32cw(std::uint32_t crc, std::uint32_t v) {
+		[[gnu::always_inline]] [[gnu::const]]
+		inline std::uint32_t neon_crc32cw(std::uint32_t crc, std::uint32_t v) {
 			__asm__ __volatile__("crc32cw %w[c], %w[c], %w[v]\n\t"
 								 : [c] "+r"(crc)
 								 : [v] "r"(v));
+			return crc;
 		}
 
-		[[gnu::always_inline]]
-		std::uint64_t neon_crc32cx (std::uint64_t crc, std::uint64_t v) {
+		[[gnu::always_inline]] [[gnu::const]]
+		inline std::uint64_t neon_crc32cx (std::uint64_t crc, std::uint64_t v) {
 			__asm__ __volatile__("crc32cx %w[c], %w[c], %x[v]\n\t"
 								 : [c] "+r"(crc)
 								 : [v] "r"(v));
+			return crc;
 		}
 	} //unnamed namespace
 
diff --git a/src/crc32/meson.build b/src/crc32/meson.build
index 4ca156c..bc51009 100644
--- a/src/crc32/meson.build
+++ b/src/crc32/meson.build
@@ -1,11 +1,20 @@
 simd = import('unstable-simd')
+
 compiler_opts = []
+if arch == 'amd64'
+  compiler_opts += ['-msse4.2']
+elif arch == 'aarch64'
+  #gcc options here:
+  #https://gcc.gnu.org/onlinedocs/gcc-11.2.0/gcc/AArch64-Options.html
+  compiler_opts += ['-mcpu=generic+crc']
+endif
 
 cpp = meson.get_compiler('cpp')
 crc32_simd = simd.check('crc32_hw',
   sse42: 'crc32_sse42.cpp',
   neon: 'crc32_neon.cpp',
   compiler: cpp,
+  cpp_args: compiler_opts,
 )
 
 crc32_objs = crc32_simd[0]
@@ -16,21 +25,11 @@ project_config_file = configure_file(
 	configuration: crc32_config
 )
 
-if get_option('wrenpp_with_sse42')
-  if arch == 'amd64'
-    compiler_opts += ['-msse4.2']
-  elif arch == 'aarch64'
-    #gcc options here:
-    #https://gcc.gnu.org/onlinedocs/gcc-11.2.0/gcc/AArch64-Options.html
-    compiler_opts += ['-mcpu=generic+crc']
-  endif
-endif
-
 crc32 = static_library('crc32',
   'crc32.cpp',
   include_directories: [public_incl],
   install: false,
-  cpp_args: compiler_opts + global_compiler_opts,
+  cpp_args: global_compiler_opts,
   link_with: crc32_objs,
 )