diff --git a/.azure-pipelines/azure-pipelines-linux-gcc.yml b/.azure-pipelines/azure-pipelines-linux-gcc.yml
index 2baf8bec6b..36b98712b9 100644
--- a/.azure-pipelines/azure-pipelines-linux-gcc.yml
+++ b/.azure-pipelines/azure-pipelines-linux-gcc.yml
@@ -29,6 +29,9 @@ jobs:
           enable_xtl_complex: 1
         gcc_9:
           gcc_version: '9'
+        gcc_9:
+          gcc_version: '9'
+          enable_fast_math: 1
     pool:
       vmImage: ubuntu-16.04
     variables:
diff --git a/.azure-pipelines/unix-build.yml b/.azure-pipelines/unix-build.yml
index 6f520acec3..8bb4b1fc72 100644
--- a/.azure-pipelines/unix-build.yml
+++ b/.azure-pipelines/unix-build.yml
@@ -39,6 +39,9 @@ steps:
       if [[ $(force_no_instr_set) == 1 ]]; then
         CMAKE_EXTRA_ARGS="$CMAKE_EXTRA_ARGS -DXSIMD_FORCE_X86_INSTR_SET=0 -DXSIMD_FORCE_X86_AMD_INSTR_SET=0";
       fi
+      if [[ $(enable_fast_math) == 1 ]]; then
+        export CXXFLAGS=-ffast-math
+      fi
 
       cmake -DCMAKE_INSTALL_PREFIX=$CONDA_PREFIX $CMAKE_EXTRA_ARGS -DDOWNLOAD_GTEST=ON -DXSIMD_ENABLE_WERROR=1 $(Build.SourcesDirectory)
     displayName: Configure xsimd