diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9692bdb407..62e4903aa2 100755
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -192,6 +192,9 @@ add_compile_options(
   -Wno-sign-compare
   -Wp,-D_GLIBCXX_ASSERTIONS
   $<$<CXX_COMPILER_ID:Clang>:-Wno-gnu-zero-variadic-macro-arguments>
+  # Needed for floating point stability in FFT (fft_test will check this).
+  # See also https://kristerw.github.io/2021/11/09/fp-contract/
+  -ffp-contract=off
   # Apple clang 14.0.0 deprecates sprintf, which generates 900 warnings.
   $<$<CXX_COMPILER_ID:AppleClang>:-Wno-deprecated-declarations>
   $<$<BOOL:${ASAN}>:-fsanitize=address>