diff --git a/ci/run_tests.sh b/ci/run_tests.sh
index d84a00f1c5..c31f134312 100755
--- a/ci/run_tests.sh
+++ b/ci/run_tests.sh
@@ -150,6 +150,10 @@ pushd preprocess_cpp_deps
 "$fpm" build
 popd
 
+pushd preprocess_cpp_suffix
+"$fpm" run
+popd
+
 pushd preprocess_per_dependency
 "$fpm" run
 popd
diff --git a/example_packages/preprocess_cpp_suffix/.gitignore b/example_packages/preprocess_cpp_suffix/.gitignore
new file mode 100644
index 0000000000..a007feab07
--- /dev/null
+++ b/example_packages/preprocess_cpp_suffix/.gitignore
@@ -0,0 +1 @@
+build/*
diff --git a/example_packages/preprocess_cpp_suffix/app/main.f90 b/example_packages/preprocess_cpp_suffix/app/main.f90
new file mode 100644
index 0000000000..7d77b56a06
--- /dev/null
+++ b/example_packages/preprocess_cpp_suffix/app/main.f90
@@ -0,0 +1,8 @@
+program test_preprocess_suffix
+   use preprocess_cpp
+#ifndef TESTMACRO
+   stop -1
+#else
+   stop 0
+#endif   
+end program test_preprocess_suffix
diff --git a/example_packages/preprocess_cpp_suffix/fpm.toml b/example_packages/preprocess_cpp_suffix/fpm.toml
new file mode 100644
index 0000000000..6399f1a67d
--- /dev/null
+++ b/example_packages/preprocess_cpp_suffix/fpm.toml
@@ -0,0 +1,7 @@
+name = "preprocess_cpp_suffix"
+version = "1"
+
+[preprocess]
+[preprocess.cpp]
+macros = ["TESTMACRO", "TESTMACRO2=3", "TESTMACRO3={version}"]
+suffixes = ["fpp"]
diff --git a/example_packages/preprocess_cpp_suffix/src/preprocess_cpp.fpp b/example_packages/preprocess_cpp_suffix/src/preprocess_cpp.fpp
new file mode 100644
index 0000000000..d7ab5d1485
--- /dev/null
+++ b/example_packages/preprocess_cpp_suffix/src/preprocess_cpp.fpp
@@ -0,0 +1,22 @@
+module preprocess_cpp
+   implicit none
+   private
+
+   public :: say_hello
+contains
+   subroutine say_hello
+      print *, "Hello, preprocess_cpp!"
+#ifndef TESTMACRO
+      This breaks the build.
+#endif
+
+#if TESTMACRO2 != 3
+      This breaks the build.
+#endif
+
+#if TESTMACRO3 != 1
+      This breaks the build.
+#endif
+
+   end subroutine say_hello
+end module preprocess_cpp
diff --git a/src/fpm.f90 b/src/fpm.f90
index 0a2712e612..bb2972bd9e 100644
--- a/src/fpm.f90
+++ b/src/fpm.f90
@@ -110,37 +110,23 @@ subroutine build_model(model, settings, package, error)
             model%packages(i)%version = package%version%s()
 
             !> Add this dependency's manifest macros
-            allocate(model%packages(i)%macros(0))
+            call model%packages(i)%preprocess%destroy()
 
             if (allocated(dependency%preprocess)) then
                 do j = 1, size(dependency%preprocess)
-                    if (dependency%preprocess(j)%name == "cpp") then
-                        if (.not. has_cpp) has_cpp = .true.
-                        if (allocated(dependency%preprocess(j)%macros)) then
-                            model%packages(i)%macros = [model%packages(i)%macros, dependency%preprocess(j)%macros]
-                        end if
-                    else
-                        write(stderr, '(a)') 'Warning: Preprocessor ' // package%preprocess(i)%name // &
-                            ' is not supported; will ignore it'
-                    end if
+                    call model%packages(i)%preprocess%add_config(dependency%preprocess(j))
                 end do
             end if
 
             !> Add this dependency's package-level macros
             if (allocated(dep%preprocess)) then
                 do j = 1, size(dep%preprocess)
-                    if (dep%preprocess(j)%name == "cpp") then
-                        if (.not. has_cpp) has_cpp = .true.
-                        if (allocated(dep%preprocess(j)%macros)) then
-                            model%packages(i)%macros = [model%packages(i)%macros, dep%preprocess(j)%macros]
-                        end if
-                    else
-                        write(stderr, '(a)') 'Warning: Preprocessor ' // package%preprocess(i)%name // &
-                            ' is not supported; will ignore it'
-                    end if
+                    call model%packages(i)%preprocess%add_config(dep%preprocess(j))
                 end do
             end if
 
+            if (model%packages(i)%preprocess%is_cpp()) has_cpp = .true.
+
             if (.not.allocated(model%packages(i)%sources)) allocate(model%packages(i)%sources(0))
 
             if (allocated(dependency%library)) then
@@ -149,7 +135,7 @@ subroutine build_model(model, settings, package, error)
                     lib_dir = join_path(dep%proj_dir, dependency%library%source_dir)
                     if (is_dir(lib_dir)) then
                         call add_sources_from_dir(model%packages(i)%sources, lib_dir, FPM_SCOPE_LIB, &
-                            error=error)
+                            with_f_ext=model%packages(i)%preprocess%suffixes, error=error)
                         if (allocated(error)) exit
                     end if
                 end if
@@ -187,7 +173,8 @@ subroutine build_model(model, settings, package, error)
     ! Add sources from executable directories
     if (is_dir('app') .and. package%build%auto_executables) then
         call add_sources_from_dir(model%packages(1)%sources,'app', FPM_SCOPE_APP, &
-                                   with_executables=.true., error=error)
+                                   with_executables=.true., with_f_ext=model%packages(1)%preprocess%suffixes,&
+                                   error=error)
 
         if (allocated(error)) then
             return
@@ -196,7 +183,8 @@ subroutine build_model(model, settings, package, error)
     end if
     if (is_dir('example') .and. package%build%auto_examples) then
         call add_sources_from_dir(model%packages(1)%sources,'example', FPM_SCOPE_EXAMPLE, &
-                                   with_executables=.true., error=error)
+                                  with_executables=.true., &
+                                  with_f_ext=model%packages(1)%preprocess%suffixes,error=error)
 
         if (allocated(error)) then
             return
@@ -205,7 +193,8 @@ subroutine build_model(model, settings, package, error)
     end if
     if (is_dir('test') .and. package%build%auto_tests) then
         call add_sources_from_dir(model%packages(1)%sources,'test', FPM_SCOPE_TEST, &
-                                   with_executables=.true., error=error)
+                                  with_executables=.true., &
+                                  with_f_ext=model%packages(1)%preprocess%suffixes,error=error)
 
         if (allocated(error)) then
             return
@@ -215,6 +204,7 @@ subroutine build_model(model, settings, package, error)
     if (allocated(package%executable)) then
         call add_executable_sources(model%packages(1)%sources, package%executable, FPM_SCOPE_APP, &
                                      auto_discover=package%build%auto_executables, &
+                                     with_f_ext=model%packages(1)%preprocess%suffixes, &
                                      error=error)
 
         if (allocated(error)) then
@@ -225,6 +215,7 @@ subroutine build_model(model, settings, package, error)
     if (allocated(package%example)) then
         call add_executable_sources(model%packages(1)%sources, package%example, FPM_SCOPE_EXAMPLE, &
                                      auto_discover=package%build%auto_examples, &
+                                     with_f_ext=model%packages(1)%preprocess%suffixes, &
                                      error=error)
 
         if (allocated(error)) then
@@ -235,6 +226,7 @@ subroutine build_model(model, settings, package, error)
     if (allocated(package%test)) then
         call add_executable_sources(model%packages(1)%sources, package%test, FPM_SCOPE_TEST, &
                                      auto_discover=package%build%auto_tests, &
+                                     with_f_ext=model%packages(1)%preprocess%suffixes, &
                                      error=error)
 
         if (allocated(error)) then
diff --git a/src/fpm/manifest/preprocess.f90 b/src/fpm/manifest/preprocess.f90
index 3f9754725a..2df2570e39 100644
--- a/src/fpm/manifest/preprocess.f90
+++ b/src/fpm/manifest/preprocess.f90
@@ -14,6 +14,7 @@ module fpm_manifest_preprocess
    use fpm_error, only : error_t, syntax_error
    use fpm_strings, only : string_t
    use fpm_toml, only : toml_table, toml_key, toml_stat, get_value, get_list
+   use,intrinsic :: iso_fortran_env, only : stderr=>error_unit
    implicit none
    private
 
@@ -39,6 +40,14 @@ module fpm_manifest_preprocess
       !> Print information on this instance
       procedure :: info
 
+      !> Operations
+      procedure :: destroy
+      procedure :: add_config
+
+      !> Properties
+      procedure :: is_cpp
+      procedure :: is_fypp
+
    end type preprocess_config_t
 
    interface operator(==)
@@ -228,4 +237,71 @@ logical function preprocess_is_same(this,that)
 
     end function preprocess_is_same
 
+    !> Clean preprocessor structure
+    elemental subroutine destroy(this)
+       class(preprocess_config_t), intent(inout) :: this
+
+       if (allocated(this%name))deallocate(this%name)
+       if (allocated(this%suffixes))deallocate(this%suffixes)
+       if (allocated(this%directories))deallocate(this%directories)
+       if (allocated(this%macros))deallocate(this%macros)
+
+    end subroutine destroy
+
+    !> Add preprocessor settings
+    subroutine add_config(this,that)
+       class(preprocess_config_t), intent(inout) :: this
+        type(preprocess_config_t), intent(in) :: that
+
+        if (.not.that%is_cpp()) then
+            write(stderr, '(a)') 'Warning: Preprocessor ' // that%name // &
+                                 ' is not supported; will ignore it'
+            return
+        end if
+
+        if (.not.allocated(this%name)) this%name = that%name
+
+        ! Add macros
+        if (allocated(that%macros)) then
+            if (allocated(this%macros)) then
+                this%macros = [this%macros, that%macros]
+            else
+                allocate(this%macros, source = that%macros)
+            end if
+        endif
+
+        ! Add suffixes
+        if (allocated(that%suffixes)) then
+            if (allocated(this%suffixes)) then
+                this%suffixes = [this%suffixes, that%suffixes]
+            else
+                allocate(this%suffixes, source = that%suffixes)
+            end if
+        endif
+
+        ! Add directories
+        if (allocated(that%directories)) then
+            if (allocated(this%directories)) then
+                this%directories = [this%directories, that%directories]
+            else
+                allocate(this%directories, source = that%directories)
+            end if
+        endif
+
+    end subroutine add_config
+
+    ! Check cpp
+    logical function is_cpp(this)
+       class(preprocess_config_t), intent(in) :: this
+       is_cpp = .false.
+       if (allocated(this%name)) is_cpp = this%name == "cpp"
+    end function is_cpp
+
+    ! Check cpp
+    logical function is_fypp(this)
+       class(preprocess_config_t), intent(in) :: this
+       is_fypp = .false.
+       if (allocated(this%name)) is_fypp = this%name == "fypp"
+    end function is_fypp
+
 end module fpm_manifest_preprocess
diff --git a/src/fpm_model.f90 b/src/fpm_model.f90
index dba15a8161..910498c2a2 100644
--- a/src/fpm_model.f90
+++ b/src/fpm_model.f90
@@ -39,6 +39,7 @@ module fpm_model
 use fpm_compiler, only: compiler_t, archiver_t, debug
 use fpm_dependency, only: dependency_tree_t
 use fpm_strings, only: string_t, str, len_trim
+use fpm_manifest_preprocess, only: preprocess_config_t
 implicit none
 
 private
@@ -137,7 +138,7 @@ module fpm_model
     type(srcfile_t), allocatable :: sources(:)
 
     !> List of macros.
-    type(string_t), allocatable :: macros(:)
+    type(preprocess_config_t) :: preprocess
 
     !> Package version number.
     character(:), allocatable :: version
diff --git a/src/fpm_sources.f90 b/src/fpm_sources.f90
index 0165249f50..69c724eec6 100644
--- a/src/fpm_sources.f90
+++ b/src/fpm_sources.f90
@@ -25,12 +25,16 @@ module fpm_sources
 
 !> Wrapper to source parsing routines.
 !> Selects parsing routine based on source file name extension
-function parse_source(source_file_path,error) result(source)
+function parse_source(source_file_path,custom_f_ext,error) result(source)
     character(*), intent(in) :: source_file_path
+    type(string_t), optional, intent(in) :: custom_f_ext(:)
     type(error_t), allocatable, intent(out) :: error
     type(srcfile_t)  :: source
+    type(string_t), allocatable :: f_ext(:)
 
-    if (str_ends_with(lower(source_file_path), fortran_suffixes)) then
+    call list_fortran_suffixes(f_ext,custom_f_ext)
+
+    if (str_ends_with(lower(source_file_path), f_ext)) then
 
         source = parse_f_source(source_file_path, error)
 
@@ -42,7 +46,7 @@ function parse_source(source_file_path,error) result(source)
 
         source = parse_c_source(source_file_path,error)
 
-    end if
+    endif
 
     if (allocated(error)) then
         return
@@ -50,8 +54,31 @@ function parse_source(source_file_path,error) result(source)
 
 end function parse_source
 
+!> List fortran suffixes, including optional ones
+subroutine list_fortran_suffixes(suffixes,with_f_ext)
+    type(string_t), allocatable, intent(out) :: suffixes(:)
+    !> Additional user-defined (preprocessor) extensions that should be treated as Fortran sources
+    type(string_t), intent(in), optional :: with_f_ext(:)
+
+    integer :: ndefault,nuser,i
+
+    ndefault = size(fortran_suffixes)
+    nuser    = 0; if (present(with_f_ext)) nuser = size(with_f_ext)
+
+    allocate(suffixes(ndefault + nuser))
+    do i=1,ndefault
+        suffixes(i) = string_t(fortran_suffixes(i))
+    end do
+    if (present(with_f_ext)) then
+        do i=1,nuser
+            suffixes(ndefault+i) = string_t(with_f_ext(i)%s)
+        end do
+    endif
+
+end subroutine list_fortran_suffixes
+
 !> Add to `sources` by looking for source files in `directory`
-subroutine add_sources_from_dir(sources,directory,scope,with_executables,recurse,error)
+subroutine add_sources_from_dir(sources,directory,scope,with_executables,with_f_ext,recurse,error)
     !> List of `[[srcfile_t]]` objects to append to. Allocated if not allocated
     type(srcfile_t), allocatable, intent(inout), target :: sources(:)
     !> Directory in which to search for source files
@@ -60,6 +87,8 @@ subroutine add_sources_from_dir(sources,directory,scope,with_executables,recurse
     integer, intent(in) :: scope
     !> Executable sources (fortran `program`s) are ignored unless `with_executables=.true.`
     logical, intent(in), optional :: with_executables
+    !> Additional user-defined (preprocessor) extensions that should be treated as Fortran sources
+    type(string_t), intent(in), optional :: with_f_ext(:)
     !> Whether to recursively search subdirectories, default is `.true.`
     logical, intent(in), optional :: recurse
     !> Error handling
@@ -69,7 +98,7 @@ subroutine add_sources_from_dir(sources,directory,scope,with_executables,recurse
     logical, allocatable :: is_source(:), exclude_source(:)
     logical :: recurse_
     type(string_t), allocatable :: file_names(:)
-    type(string_t), allocatable :: src_file_names(:)
+    type(string_t), allocatable :: src_file_names(:),f_ext(:)
     type(string_t), allocatable :: existing_src_files(:)
     type(srcfile_t), allocatable :: dir_sources(:)
 
@@ -87,10 +116,15 @@ subroutine add_sources_from_dir(sources,directory,scope,with_executables,recurse
         allocate(existing_src_files(0))
     end if
 
+    ! Get legal fortran suffixes
+    call list_fortran_suffixes(f_ext,with_f_ext)
+
     is_source = [(.not.(is_hidden_file(basename(file_names(i)%s))) .and. &
                  .not.(canon_path(file_names(i)%s) .in. existing_src_files) .and. &
-                 (str_ends_with(lower(file_names(i)%s), fortran_suffixes) .or. &
+                 (str_ends_with(lower(file_names(i)%s), f_ext) .or. &
                  str_ends_with(lower(file_names(i)%s), c_suffixes) ),i=1,size(file_names))]
+
+
     src_file_names = pack(file_names,is_source)
 
     allocate(dir_sources(size(src_file_names)))
@@ -98,7 +132,7 @@ subroutine add_sources_from_dir(sources,directory,scope,with_executables,recurse
 
     do i = 1, size(src_file_names)
 
-        dir_sources(i) = parse_source(src_file_names(i)%s,error)
+        dir_sources(i) = parse_source(src_file_names(i)%s,with_f_ext,error)
         if (allocated(error)) return
 
         dir_sources(i)%unit_scope = scope
@@ -129,7 +163,7 @@ end subroutine add_sources_from_dir
 !> Add to `sources` using the executable and test entries in the manifest and
 !> applies any executable-specific overrides such as `executable%name`.
 !> Adds all sources (including modules) from each `executable%source_dir`
-subroutine add_executable_sources(sources,executables,scope,auto_discover,error)
+subroutine add_executable_sources(sources,executables,scope,auto_discover,with_f_ext,error)
     !> List of `[[srcfile_t]]` objects to append to. Allocated if not allocated
     type(srcfile_t), allocatable, intent(inout), target :: sources(:)
     !> List of `[[executable_config_t]]` entries from manifest
@@ -138,6 +172,8 @@ subroutine add_executable_sources(sources,executables,scope,auto_discover,error)
     integer, intent(in) :: scope
     !> If `.false.` only executables and tests specified in the manifest are added to `sources`
     logical, intent(in) :: auto_discover
+    !> Additional user-defined (preprocessor) extensions that should be treated as Fortran sources
+    type(string_t), intent(in), optional :: with_f_ext(:)
     !> Error handling
     type(error_t), allocatable, intent(out) :: error
 
@@ -150,7 +186,7 @@ subroutine add_executable_sources(sources,executables,scope,auto_discover,error)
 
     do i=1,size(exe_dirs)
         call add_sources_from_dir(sources,exe_dirs(i)%s, scope, &
-                     with_executables=auto_discover, recurse=.false., error=error)
+                     with_executables=auto_discover, with_f_ext=with_f_ext,recurse=.false., error=error)
 
         if (allocated(error)) then
             return
@@ -180,7 +216,7 @@ subroutine add_executable_sources(sources,executables,scope,auto_discover,error)
 
         ! Add if not already discovered (auto_discovery off)
         associate(exe => executables(i))
-            exe_source = parse_source(join_path(exe%source_dir,exe%main),error)
+            exe_source = parse_source(join_path(exe%source_dir,exe%main),with_f_ext,error)
             exe_source%exe_name = exe%name
             if (allocated(exe%link)) then
                 exe_source%link_libraries = exe%link
diff --git a/src/fpm_strings.f90 b/src/fpm_strings.f90
index 55f57537e5..c3187db786 100644
--- a/src/fpm_strings.f90
+++ b/src/fpm_strings.f90
@@ -76,6 +76,7 @@ module fpm_strings
 interface str_ends_with
     procedure :: str_ends_with_str
     procedure :: str_ends_with_any
+    procedure :: str_ends_with_any_string
 end interface str_ends_with
 
 interface str
@@ -122,6 +123,23 @@ pure logical function str_ends_with_any(s, e) result(r)
 
 end function str_ends_with_any
 
+!> Test if a CHARACTER string ends with any of an array of string suffixs
+pure logical function str_ends_with_any_string(s, e) result(r)
+    character(*), intent(in) :: s
+    type(string_t), intent(in) :: e(:)
+
+    integer :: i
+
+    r = .true.
+    do i=1,size(e)
+
+        if (str_ends_with(s,trim(e(i)%s))) return
+
+    end do
+    r = .false.
+
+end function str_ends_with_any_string
+
 !> test if a CHARACTER string begins with a specified prefix
 pure logical function str_begins_with_str(s, e, case_sensitive) result(r)
     character(*), intent(in) :: s, e
diff --git a/src/fpm_targets.f90 b/src/fpm_targets.f90
index df0d58810f..7c8c97b775 100644
--- a/src/fpm_targets.f90
+++ b/src/fpm_targets.f90
@@ -33,6 +33,7 @@ module fpm_targets
 use fpm_strings, only: string_t, operator(.in.), string_cat, fnv_1a, resize, lower, str_ends_with
 use fpm_compiler, only: get_macros
 use fpm_sources, only: get_exe_name_with_suffix
+use fpm_manifest_preprocess, only: preprocess_config_t
 implicit none
 
 private
@@ -233,7 +234,7 @@ subroutine build_target_list(targets,model)
                                                sources(i)%unit_type==FPM_UNIT_CSOURCE), &
                                 output_name = get_object_name(sources(i)), &
                                 features = model%packages(j)%features, &
-                                macros = model%packages(j)%macros, &
+                                preprocess = model%packages(j)%preprocess, &
                                 version = model%packages(j)%version)
 
 
@@ -247,7 +248,7 @@ subroutine build_target_list(targets,model)
                     call add_target(targets,package=model%packages(j)%name,source = sources(i), &
                                 type = FPM_TARGET_CPP_OBJECT, &
                                 output_name = get_object_name(sources(i)), &
-                                macros = model%packages(j)%macros, &
+                                preprocess = model%packages(j)%preprocess, &
                                 version = model%packages(j)%version)
 
                     if (with_lib .and. sources(i)%unit_scope == FPM_SCOPE_LIB) then
@@ -280,7 +281,7 @@ subroutine build_target_list(targets,model)
                                 output_name = get_object_name(sources(i)), &
                                 source = sources(i), &
                                 features = model%packages(j)%features, &
-                                macros = model%packages(j)%macros &
+                                preprocess = model%packages(j)%preprocess &
                                 )
 
                     if (sources(i)%unit_scope == FPM_SCOPE_APP) then
@@ -413,7 +414,7 @@ end subroutine collect_exe_link_dependencies
 
 !> Allocate a new target and append to target list
 subroutine add_target(targets, package, type, output_name, source, link_libraries, &
-        & features, macros, version)
+        & features, preprocess, version)
     type(build_target_ptr), allocatable, intent(inout) :: targets(:)
     character(*), intent(in) :: package
     integer, intent(in) :: type
@@ -421,7 +422,7 @@ subroutine add_target(targets, package, type, output_name, source, link_librarie
     type(srcfile_t), intent(in), optional :: source
     type(string_t), intent(in), optional :: link_libraries(:)
     type(fortran_features_t), intent(in), optional :: features
-    type(string_t), intent(in), optional :: macros(:)
+    type(preprocess_config_t), intent(in), optional :: preprocess
     character(*), intent(in), optional :: version
 
     integer :: i
@@ -450,7 +451,9 @@ subroutine add_target(targets, package, type, output_name, source, link_librarie
     if (present(source)) new_target%source = source
     if (present(link_libraries)) new_target%link_libraries = link_libraries
     if (present(features)) new_target%features = features
-    if (present(macros)) new_target%macros = macros
+    if (present(preprocess)) then
+        if (allocated(preprocess%macros)) new_target%macros = preprocess%macros
+    endif
     if (present(version)) new_target%version = version
     allocate(new_target%dependencies(0))