diff --git a/GraphBLAS/cmake_modules/SuiteSparsePolicy.cmake b/GraphBLAS/cmake_modules/SuiteSparsePolicy.cmake
index f2d132aa74..20a7fcf784 100644
--- a/GraphBLAS/cmake_modules/SuiteSparsePolicy.cmake
+++ b/GraphBLAS/cmake_modules/SuiteSparsePolicy.cmake
@@ -247,6 +247,19 @@ message ( STATUS "Build type:       ${CMAKE_BUILD_TYPE} ")
 
 set ( CMAKE_INCLUDE_CURRENT_DIR ON )
 
+#-------------------------------------------------------------------------------
+# Workaround for math.h on old macOS
+#-------------------------------------------------------------------------------
+
+if ( APPLE AND CMAKE_SYSTEM_VERSION VERSION_LESS 11 )
+    # Older versions of math.h on the Mac define Real and Imag, which
+    # conflict with the internal use of those symbols in CHOLMOD, KLU, SPQR,
+    # UMFPACK, and ParU.
+    # This can be disabled with -D__NOEXTENSIONS__
+    message ( STATUS "MacOS: disable extensions in math.h" )
+    add_compile_definitions ( "__NOEXTENSIONS__" )
+endif ( )
+
 #-------------------------------------------------------------------------------
 # check if Fortran is available and enabled
 #-------------------------------------------------------------------------------
diff --git a/LAGraph/cmake_modules/SuiteSparsePolicy.cmake b/LAGraph/cmake_modules/SuiteSparsePolicy.cmake
index f2d132aa74..20a7fcf784 100644
--- a/LAGraph/cmake_modules/SuiteSparsePolicy.cmake
+++ b/LAGraph/cmake_modules/SuiteSparsePolicy.cmake
@@ -247,6 +247,19 @@ message ( STATUS "Build type:       ${CMAKE_BUILD_TYPE} ")
 
 set ( CMAKE_INCLUDE_CURRENT_DIR ON )
 
+#-------------------------------------------------------------------------------
+# Workaround for math.h on old macOS
+#-------------------------------------------------------------------------------
+
+if ( APPLE AND CMAKE_SYSTEM_VERSION VERSION_LESS 11 )
+    # Older versions of math.h on the Mac define Real and Imag, which
+    # conflict with the internal use of those symbols in CHOLMOD, KLU, SPQR,
+    # UMFPACK, and ParU.
+    # This can be disabled with -D__NOEXTENSIONS__
+    message ( STATUS "MacOS: disable extensions in math.h" )
+    add_compile_definitions ( "__NOEXTENSIONS__" )
+endif ( )
+
 #-------------------------------------------------------------------------------
 # check if Fortran is available and enabled
 #-------------------------------------------------------------------------------
diff --git a/SuiteSparse_config/cmake_modules/SuiteSparsePolicy.cmake b/SuiteSparse_config/cmake_modules/SuiteSparsePolicy.cmake
index f2d132aa74..20a7fcf784 100644
--- a/SuiteSparse_config/cmake_modules/SuiteSparsePolicy.cmake
+++ b/SuiteSparse_config/cmake_modules/SuiteSparsePolicy.cmake
@@ -247,6 +247,19 @@ message ( STATUS "Build type:       ${CMAKE_BUILD_TYPE} ")
 
 set ( CMAKE_INCLUDE_CURRENT_DIR ON )
 
+#-------------------------------------------------------------------------------
+# Workaround for math.h on old macOS
+#-------------------------------------------------------------------------------
+
+if ( APPLE AND CMAKE_SYSTEM_VERSION VERSION_LESS 11 )
+    # Older versions of math.h on the Mac define Real and Imag, which
+    # conflict with the internal use of those symbols in CHOLMOD, KLU, SPQR,
+    # UMFPACK, and ParU.
+    # This can be disabled with -D__NOEXTENSIONS__
+    message ( STATUS "MacOS: disable extensions in math.h" )
+    add_compile_definitions ( "__NOEXTENSIONS__" )
+endif ( )
+
 #-------------------------------------------------------------------------------
 # check if Fortran is available and enabled
 #-------------------------------------------------------------------------------