diff --git a/src/build/llvmPackages.ts b/src/build/llvmPackages.ts
index 44cfe44..306d00c 100644
--- a/src/build/llvmPackages.ts
+++ b/src/build/llvmPackages.ts
@@ -156,8 +156,8 @@ export function llvmPackages({
                     definitions: variable({
                         ...general,
                         ...{
-                            CMAKE_C_FLAGS: "-msimd",
-                            CMAKE_CXX_FLAGS: "-msimd",
+                            CMAKE_C_FLAGS: "-msimd -mlong-double-64",
+                            CMAKE_CXX_FLAGS: "-msimd -mlong-double-64",
                             CMAKE_C_COMPILER: path.join(installPrefix, "bin", "clang"),
                             CMAKE_CXX_COMPILER: path.join(installPrefix, "bin", "clang++"),
                         } as GeneralVariable,