diff --git a/Documentation/source/glossary.rst b/Documentation/source/glossary.rst
index b9ff75cb..ec97cc9d 100644
--- a/Documentation/source/glossary.rst
+++ b/Documentation/source/glossary.rst
@@ -65,7 +65,9 @@ Glossary
         A folder inside the :term:`Fab Workspace`, containing all source and output from a build config.
 
     Root Symbol
-        The name of a Fortran PROGRAM, or ``"main"`` for C code. Fab builds an executable for every root symbol it's given.
+        The name of a Fortran PROGRAM, or ``"main"`` for C code. Fab builds an executable for every root symbol it's given. Internally, any ``main``
+        symbol will be suffixed with the name of the C file, which allows
+        Fab to manage several C main programs in one build tree.
 
     Source Tree
         The :class:`~fab.steps.analyse.analyse` step produces a dependency tree of the entire project source.
diff --git a/source/fab/dep_tree.py b/source/fab/dep_tree.py
index e61949f2..82c04972 100644
--- a/source/fab/dep_tree.py
+++ b/source/fab/dep_tree.py
@@ -4,11 +4,13 @@
 # which you should have received as part of this distribution
 ##############################################################################
 """
-Classes and helper functions related to the dependency tree, as created by the analysis stage.
+Classes and helper functions related to the dependency tree, as created by
+the analysis stage.
 
 """
 
-# todo: we've since adopted the term "source tree", so we should probably rename this module to match.
+# todo: we've since adopted the term "source tree", so we should probably
+# rename this module to match.
 from abc import ABC
 import logging
 from pathlib import Path
@@ -20,18 +22,24 @@
 
 
 # Todo: Better name? It's an analysed file in a dependency tree
-#       (as opposed to an analysed x90 for example, which isn't part of this tree dependency analysis).
+#       (as opposed to an analysed x90 for example, which isn't part of this
+#       tree dependency analysis).
 class AnalysedDependent(AnalysedFile, ABC):
     """
-    An :class:`~fab.parse.AnalysedFile` which can depend on others, and be a dependency.
-    Instances of this class are nodes in a source dependency tree.
+    An :class:`~fab.parse.AnalysedFile` which can depend on others, and be
+    a dependency. Instances of this class are nodes in a source dependency
+    tree.
 
     During parsing, the symbol definitions and dependencies are filled in.
-    During dependency analysis, symbol dependencies are turned into file dependencies.
+    During dependency analysis, symbol dependencies are turned into file
+    dependencies.
 
     """
-    def __init__(self, fpath: Union[str, Path], file_hash: Optional[int] = None,
-                 symbol_defs: Optional[Iterable[str]] = None, symbol_deps: Optional[Iterable[str]] = None,
+    def __init__(self,
+                 fpath: Union[str, Path],
+                 file_hash: Optional[int] = None,
+                 symbol_defs: Optional[Iterable[str]] = None,
+                 symbol_deps: Optional[Iterable[str]] = None,
                  file_deps: Optional[Iterable[Path]] = None):
         """
         :param fpath:
@@ -45,7 +53,8 @@ def __init__(self, fpath: Union[str, Path], file_hash: Optional[int] = None,
             Can include symbols in the same file.
         :param file_deps:
             Other files on which this source depends. Must not include itself.
-            This attribute is calculated during symbol analysis, after everything has been parsed.
+            This attribute is calculated during symbol analysis, after
+            everything has been parsed.
 
         """
         super().__init__(fpath=fpath, file_hash=file_hash)
@@ -54,19 +63,34 @@ def __init__(self, fpath: Union[str, Path], file_hash: Optional[int] = None,
         self.symbol_deps: set[str] = set(symbol_deps or {})
         self.file_deps: set[Path] = set(file_deps or [])
 
-        assert all([d and len(d) for d in self.symbol_defs]), "bad symbol definitions"
-        assert all([d and len(d) for d in self.symbol_deps]), "bad symbol dependencies"
+        assert all([d and len(d) for d in self.symbol_defs]), \
+            "bad symbol definitions"
+        assert all([d and len(d) for d in self.symbol_deps]), \
+            "bad symbol dependencies"
 
-    def add_symbol_def(self, name):
+    def add_symbol_def(self, name: str) -> None:
+        """
+        Adds a symbol definition.
+
+        :param name: the symbol name to add.
+        """
         assert name and len(name)
-        self.symbol_defs.add(name.lower())
+        self.symbol_defs.add(name)
+
+    def add_symbol_dep(self, name: str) -> None:
+        """
+        Adds a dependency to a symbol.
 
-    def add_symbol_dep(self, name):
+        :param name: name of the symbol that is required.
+        """
         assert name and len(name)
-        self.symbol_deps.add(name.lower())
+        self.symbol_deps.add(name)
 
-    def add_file_dep(self, name):
-        self.file_deps.add(Path(name))
+    def add_file_dep(self, file_name: str) -> None:
+        """
+        Adds a dependency to a file;
+        """
+        self.file_deps.add(Path(file_name))
 
     @classmethod
     def field_names(cls):
@@ -99,20 +123,23 @@ def from_dict(cls, d):
 
 
 def extract_sub_tree(source_tree: dict[Path, AnalysedDependent],
-                     root: Path, verbose=False)\
+                     root: Path,
+                     verbose=False)\
         -> dict[Path, AnalysedDependent]:
     """
-    Extract the subtree required to build the target, from the full source tree of all analysed source files.
+    Extract the subtree required to build the target, from the full
+    source tree of all analysed source files.
 
     :param source_tree:
         The source tree of analysed files.
     :param root:
-        The root of the dependency tree, this is the filename containing the Fortran program.
+        The root of the dependency tree, this is the filename containing the
+        Fortran program.
     :param verbose:
         Log missing dependencies.
 
     """
-    result: dict[Path, AnalysedDependent] = dict()
+    result: dict[Path, AnalysedDependent] = {}
     missing: set[Path] = set()
 
     _extract_sub_tree(src_tree=source_tree,
@@ -157,10 +184,12 @@ def _extract_sub_tree(src_tree: dict[Path, AnalysedDependent],
 
         # add this child dep
         _extract_sub_tree(
-            src_tree=src_tree, key=file_dep, dst_tree=dst_tree, missing=missing, verbose=verbose, indent=indent + 1)
+            src_tree=src_tree, key=file_dep, dst_tree=dst_tree,
+            missing=missing, verbose=verbose, indent=indent + 1)
 
 
-def filter_source_tree(source_tree: dict[Path, AnalysedDependent], suffixes: Iterable[str]) -> list[AnalysedDependent]:
+def filter_source_tree(source_tree: dict[Path, AnalysedDependent],
+                       suffixes: Iterable[str]) -> list[AnalysedDependent]:
     """
     Pull out files with the given extensions from a source tree.
 
@@ -178,7 +207,8 @@ def filter_source_tree(source_tree: dict[Path, AnalysedDependent], suffixes: Ite
 
 def validate_dependencies(source_tree):
     """
-    If any dep is missing from the tree, then it's unknown code and we won't be able to compile.
+    If any dep is missing from the tree, then it's unknown code and we won't
+    be able to compile.
 
     :param source_tree:
         The source tree of analysed files.
@@ -186,7 +216,9 @@ def validate_dependencies(source_tree):
     """
     missing = set()
     for f in source_tree.values():
-        missing.update([str(file_dep) for file_dep in f.file_deps if file_dep not in source_tree])
+        missing.update([str(file_dep) for file_dep in f.file_deps
+                        if file_dep not in source_tree])
 
     if missing:
-        logger.error(f"Unknown dependencies, expecting build to fail: {', '.join(sorted(missing))}")
+        logger.error(f"Unknown dependencies, expecting build to fail: "
+                     f"{', '.join(sorted(missing))}")
diff --git a/source/fab/parse/c.py b/source/fab/parse/c.py
index 63a844c4..504bd419 100644
--- a/source/fab/parse/c.py
+++ b/source/fab/parse/c.py
@@ -175,7 +175,13 @@ def _process_symbol_declaration(self, analysed_file, node, usr_symbols):
                 # the rest of the application
                 logger.debug('  * Is defined in this file')
                 # todo: ignore if inside user pragmas?
-                analysed_file.add_symbol_def(node.spelling)
+                if node.spelling == "main":
+                    # To allow multiple main programs in c, change the
+                    # 'main' symbol to include the file name:
+                    main_symbol = f"main@{analysed_file.fpath.stem}"
+                    analysed_file.add_symbol_def(main_symbol)
+                else:
+                    analysed_file.add_symbol_def(node.spelling)
         else:
             # Record any user included symbols in case they're referenced later in the code
             if self._check_for_include(node.location.line) == "usr_include":
diff --git a/source/fab/parse/fortran.py b/source/fab/parse/fortran.py
index 04b2bdb3..ff76601e 100644
--- a/source/fab/parse/fortran.py
+++ b/source/fab/parse/fortran.py
@@ -95,6 +95,20 @@ def __init__(self, fpath: Union[str, Path],
 
         self.validate()
 
+    def add_symbol_def(self, name: str):
+        """
+        Add a Fortran symbol definition, which is case independent.
+        """
+        assert name and len(name)
+        super().add_symbol_def(name.lower())
+
+    def add_symbol_dep(self, name: str):
+        """
+        Add a Fortran dependency, which is case independent
+        """
+        assert name and len(name)
+        super().add_symbol_dep(name.lower())
+
     def add_program_def(self, name):
         self.program_defs.add(name.lower())
         self.add_symbol_def(name)
diff --git a/source/fab/steps/analyse.py b/source/fab/steps/analyse.py
index 4c369b02..4f2ad4ff 100644
--- a/source/fab/steps/analyse.py
+++ b/source/fab/steps/analyse.py
@@ -40,7 +40,6 @@
 from pathlib import Path
 from typing import Iterable, Optional, Union
 
-from fab import FabException
 from fab.artefacts import ArtefactsGetter, ArtefactSet, CollectionConcat
 from fab.dep_tree import extract_sub_tree, validate_dependencies, AnalysedDependent
 from fab.mo import add_mo_commented_file_deps
@@ -149,7 +148,9 @@ def analyse(
 
     # parse
     files: list[Path] = source_getter(config.artefact_store)
-    analysed_files = _parse_files(config, files=files, fortran_analyser=fortran_analyser, c_analyser=c_analyser)
+    analysed_files = _parse_files(config, files=files,
+                                  fortran_analyser=fortran_analyser,
+                                  c_analyser=c_analyser)
     _add_manual_results(special_measure_analysis_results, analysed_files)
 
     # shall we search the results for fortran programs and a c function called main?
@@ -157,13 +158,15 @@ def analyse(
         # find fortran programs
         sets_of_programs = [af.program_defs for af in by_type(analysed_files, AnalysedFortran)]
         root_symbols = list(chain(*sets_of_programs))
-
-        # find c main()
-        c_with_main = list(filter(lambda c: 'main' in c.symbol_defs, by_type(analysed_files, AnalysedC)))
-        if c_with_main:
-            root_symbols.append('main')
-            if len(c_with_main) > 1:
-                raise FabException("multiple c main() functions found")
+        # find c main() symbols. In order to support building multiple
+        # C programs, each `main` symbol is replaced with `main@filename` during
+        # parsing.
+        for analysed_c in analysed_files:
+            if not isinstance(analysed_c, AnalysedC):
+                continue
+            main_symbol = f"main@{analysed_c.fpath.stem}"
+            if main_symbol in analysed_c.symbol_defs:
+                root_symbols.append(main_symbol)
 
         logger.info(f'automatically found the following programs to build: {", ".join(root_symbols)}')
 
diff --git a/source/fab/steps/link.py b/source/fab/steps/link.py
index 78736b78..94f58f1e 100644
--- a/source/fab/steps/link.py
+++ b/source/fab/steps/link.py
@@ -93,6 +93,8 @@ def link_exe(config,
     flags = flags or []
 
     for root, objects in target_objects.items():
+        if root.startswith("main@"):
+            root = root[len("main@"):]
         exe_path = config.project_workspace / f'{root}'
         linker.link(objects, exe_path, config=config, libs=libs,
                     add_flags=flags)
diff --git a/tests/system_tests/CFortranInterop/test_CFortranInterop.py b/tests/system_tests/CFortranInterop/test_CFortranInterop.py
index 84c01347..0db00a87 100644
--- a/tests/system_tests/CFortranInterop/test_CFortranInterop.py
+++ b/tests/system_tests/CFortranInterop/test_CFortranInterop.py
@@ -35,7 +35,7 @@ def test_CFortranInterop(tmp_path):
         c_pragma_injector(config)
         preprocess_c(config)
         preprocess_fortran(config)
-        analyse(config, root_symbols='main')
+        analyse(config, root_symbols='main@c_roundtrip')
         compile_c(config, common_flags=['-c', '-std=c99'])
         with warns(UserWarning, match="Removing managed flag"):
             compile_fortran(config, common_flags=['-c'])
diff --git a/tests/system_tests/CUserHeader/test_CUserHeader.py b/tests/system_tests/CUserHeader/test_CUserHeader.py
index 1a376884..018d4f86 100644
--- a/tests/system_tests/CUserHeader/test_CUserHeader.py
+++ b/tests/system_tests/CUserHeader/test_CUserHeader.py
@@ -34,7 +34,7 @@ def test_CUseHeader(tmp_path):
         find_source_files(config)
         c_pragma_injector(config)
         preprocess_c(config)
-        analyse(config, root_symbols='main')
+        analyse(config, root_symbols='main@mainprog')
         compile_c(config, common_flags=['-c', '-std=c99'])
         link_exe(config, flags=['-lgfortran'])
 
@@ -44,4 +44,6 @@ def test_CUseHeader(tmp_path):
     command = [str(list(config.artefact_store[ArtefactSet.EXECUTABLES])[0])]
     res = subprocess.run(command, capture_output=True)
     output = res.stdout.decode()
-    assert output == ''.join(open(PROJECT_SOURCE / 'expected.exec.txt').readlines())
+    with open(PROJECT_SOURCE / 'expected.exec.txt', 'r',
+              encoding="utf-8") as fd:
+        assert output == ''.join(fd.readlines())
diff --git a/tests/system_tests/MinimalC/test_MinimalC.py b/tests/system_tests/MinimalC/test_MinimalC.py
index 7959fd17..7431fca0 100644
--- a/tests/system_tests/MinimalC/test_MinimalC.py
+++ b/tests/system_tests/MinimalC/test_MinimalC.py
@@ -34,7 +34,7 @@ def test_minimal_c(tmp_path):
         find_source_files(config)
         c_pragma_injector(config)
         preprocess_c(config)
-        analyse(config, root_symbols='main')
+        analyse(config, root_symbols='main@main')
         compile_c(config, common_flags=['-c', '-std=c99'])
         link_exe(config)
 
diff --git a/tests/system_tests/zero_config/test_zero_config.py b/tests/system_tests/zero_config/test_zero_config.py
index abbeb95a..b33b3e56 100644
--- a/tests/system_tests/zero_config/test_zero_config.py
+++ b/tests/system_tests/zero_config/test_zero_config.py
@@ -57,7 +57,7 @@ def test_c(self, tmp_path: Path) -> None:
                   'fab_workspace': tmp_path,
                   'multiprocessing': False}
         config = cli_fab(folder=tmp_path / 'source', kwargs=kwargs)
-        assert (config.project_workspace / 'main').exists()
+        assert (config.project_workspace / 'mainprog').exists()
 
     def test_c_fortran(self, tmp_path: Path) -> None:
         """
@@ -75,4 +75,4 @@ def test_c_fortran(self, tmp_path: Path) -> None:
                   'fab_workspace': tmp_path / 'fab',
                   'multiprocessing': False}
         config = cli_fab(folder=tmp_path / 'source', kwargs=kwargs)
-        assert (config.project_workspace / 'main').exists()
+        assert (config.project_workspace / 'c_roundtrip').exists()
diff --git a/tests/unit_tests/parse/c/other_main_program.c b/tests/unit_tests/parse/c/other_main_program.c
new file mode 100644
index 00000000..7b38e4f4
--- /dev/null
+++ b/tests/unit_tests/parse/c/other_main_program.c
@@ -0,0 +1,12 @@
+
+/* Just a mostly empty program to check that
+   multiple c main programs work as expected, and that C symbols are
+   stored case sensitive
+*/
+
+int CaSeSeNsItIvE() {                // external linkage, is a definition
+    return 1;
+}
+
+void main(void) {               // external linkage, is a definition
+}
diff --git a/tests/unit_tests/parse/c/test_c_analyser.py b/tests/unit_tests/parse/c/test_c_analyser.py
index 4341ba4c..26274d01 100644
--- a/tests/unit_tests/parse/c/test_c_analyser.py
+++ b/tests/unit_tests/parse/c/test_c_analyser.py
@@ -30,12 +30,25 @@ def test_simple_result(tmp_path: Path,
         fpath=fpath,
         file_hash=1429445462,
         symbol_deps={'usr_var', 'usr_func'},
-        symbol_defs={'func_decl', 'func_def', 'var_def', 'var_extern_def', 'main'},
+        symbol_defs={'func_decl', 'func_def', 'var_def', 'var_extern_def',
+                     'main@test_c_analyser'},
     )
     assert analysis == expected
     assert isinstance(analysis, AnalysedC)
     assert artefact == c_analyser._config.prebuild_folder / f'test_c_analyser.{analysis.file_hash}.an'
 
+    with mock.patch('fab.parse.AnalysedFile.save'):
+        fpath = Path(__file__).parent / "other_main_program.c"
+        analysis, artefact = c_analyser.run(fpath)
+
+    expected = AnalysedC(
+        fpath=fpath,
+        file_hash=1458424101,
+        symbol_deps={},
+        symbol_defs={'CaSeSeNsItIvE', 'main@other_main_program'},
+    )
+    assert analysis == expected
+
 
 class Test__locate_include_regions: