diff --git a/modules/fc-optional.cmake b/modules/fc-optional.cmake
new file mode 100644
index 0000000..6d940c9
--- /dev/null
+++ b/modules/fc-optional.cmake
@@ -0,0 +1,69 @@
+#.rst:
+#
+# Adds optional Fortran support.
+# Appends EXTRA_FCFLAGS to CMAKE_Fortran_FLAGS.
+# If environment variable FCFLAGS is set, then the FCFLAGS are used
+# and no other flags are used or appended.
+#
+# Variables used::
+#
+#   EXTRA_FCFLAGS
+#   ENABLE_FC_SUPPORT
+#
+# Variables defined::
+#
+#   CMAKE_Fortran_MODULE_DIRECTORY (${PROJECT_BINARY_DIR}/include/fortran)
+#
+# Variables modified::
+#
+#   CMAKE_Fortran_FLAGS
+#
+# Variables set::
+#
+#   ENABLE_FC_SUPPORT
+#
+# Environment variables used::
+#
+#   FCFLAGS
+#
+# Example autocmake.cfg entry::
+#
+#   [fc]
+#   source: https://github.com/scisoft/autocmake/raw/master/modules/fc.cmake
+#   docopt: --fc=<FC> Fortran compiler [default: gfortran].
+#           --extra-fc-flags=<EXTRA_FCFLAGS> Extra Fortran compiler flags [default: ''].
+#           --fc-support=<FC_SUPPORT> Toggle Fortran language support (ON/OFF) [default: ON].
+#   export: 'FC=%s' % arguments['--fc']
+#   define: '-DEXTRA_FCFLAGS="%s"' % arguments['--extra-fc-flags']
+#           '-DENABLE_FC_SUPPORT="%s"' % arguments['--fc-support']
+
+option(ENABLE_FC_SUPPORT "Enable Fortran language support" ON)
+
+if(ENABLE_FC_SUPPORT)
+    enable_language(Fortran)
+
+    set(CMAKE_Fortran_MODULE_DIRECTORY ${PROJECT_BINARY_DIR}/include/fortran)
+
+    if(NOT DEFINED CMAKE_Fortran_COMPILER_ID)
+        message(FATAL_ERROR "CMAKE_Fortran_COMPILER_ID variable is not defined!")
+    endif()
+
+    if(NOT CMAKE_Fortran_COMPILER_WORKS)
+        message(FATAL_ERROR "CMAKE_Fortran_COMPILER_WORKS is false!")
+    endif()
+
+    if(DEFINED EXTRA_FCFLAGS)
+        set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} ${EXTRA_FCFLAGS}")
+    endif()
+
+    if(DEFINED ENV{FCFLAGS})
+        message(STATUS "FCFLAGS is set to '$ENV{FCFLAGS}'.")
+        set(CMAKE_Fortran_FLAGS "$ENV{FCFLAGS}")
+    endif()
+else()
+    # workaround to avoid unused warning
+    if(DEFINED EXTRA_FCFLAGS)
+        set(_unused ${EXTRA_FCFLAGS})
+        unset(_unused)
+    endif()
+endif()
diff --git a/modules/fc.cmake b/modules/fc.cmake
index f2b2339..c4b005f 100644
--- a/modules/fc.cmake
+++ b/modules/fc.cmake
@@ -8,7 +8,6 @@
 # Variables used::
 #
 #   EXTRA_FCFLAGS
-#   ENABLE_FC_SUPPORT
 #
 # Variables defined::
 #
@@ -18,10 +17,6 @@
 #
 #   CMAKE_Fortran_FLAGS
 #
-# Variables set::
-#
-#   ENABLE_FC_SUPPORT
-#
 # Environment variables used::
 #
 #   FCFLAGS
@@ -32,38 +27,26 @@
 #   source: https://github.com/scisoft/autocmake/raw/master/modules/fc.cmake
 #   docopt: --fc=<FC> Fortran compiler [default: gfortran].
 #           --extra-fc-flags=<EXTRA_FCFLAGS> Extra Fortran compiler flags [default: ''].
-#           --fc-support=<FC_SUPPORT> Toggle Fortran language support (ON/OFF) [default: ON].
 #   export: 'FC=%s' % arguments['--fc']
 #   define: '-DEXTRA_FCFLAGS="%s"' % arguments['--extra-fc-flags']
-#           '-DENABLE_FC_SUPPORT="%s"' % arguments['--fc-support']
 
-option(ENABLE_FC_SUPPORT "Enable Fortran language support" ON)
+enable_language(Fortran)
 
-if(ENABLE_FC_SUPPORT)
-    enable_language(Fortran)
+set(CMAKE_Fortran_MODULE_DIRECTORY ${PROJECT_BINARY_DIR}/include/fortran)
 
-    set(CMAKE_Fortran_MODULE_DIRECTORY ${PROJECT_BINARY_DIR}/include/fortran)
-
-    if(NOT DEFINED CMAKE_Fortran_COMPILER_ID)
-        message(FATAL_ERROR "CMAKE_Fortran_COMPILER_ID variable is not defined!")
-    endif()
-
-    if(NOT CMAKE_Fortran_COMPILER_WORKS)
-        message(FATAL_ERROR "CMAKE_Fortran_COMPILER_WORKS is false!")
-    endif()
-
-    if(DEFINED EXTRA_FCFLAGS)
-        set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} ${EXTRA_FCFLAGS}")
-    endif()
-
-    if(DEFINED ENV{FCFLAGS})
-        message(STATUS "FCFLAGS is set to '$ENV{FCFLAGS}'.")
-        set(CMAKE_Fortran_FLAGS "$ENV{FCFLAGS}")
-    endif()
-else()
-    # workaround to avoid unused warning
-    if(DEFINED EXTRA_FCFLAGS)
-        set(_unused ${EXTRA_FCFLAGS})
-        unset(_unused)
-    endif()
+if(NOT DEFINED CMAKE_Fortran_COMPILER_ID)
+    message(FATAL_ERROR "CMAKE_Fortran_COMPILER_ID variable is not defined!")
+endif()
+
+if(NOT CMAKE_Fortran_COMPILER_WORKS)
+    message(FATAL_ERROR "CMAKE_Fortran_COMPILER_WORKS is false!")
+endif()
+
+if(DEFINED EXTRA_FCFLAGS)
+    set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} ${EXTRA_FCFLAGS}")
+endif()
+
+if(DEFINED ENV{FCFLAGS})
+    message(STATUS "FCFLAGS is set to '$ENV{FCFLAGS}'.")
+    set(CMAKE_Fortran_FLAGS "$ENV{FCFLAGS}")
 endif()