diff --git a/CHANGELOG.md b/CHANGELOG.md
index 171ca17..99cf68b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,8 +11,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add new parameters to `bss_check.printSymbolComparison`.
   - `printGoods`: Allows toggling printing the GOOD symbols.
-  - `printingStyle`: The style to use to print the symbols, either `"csv"` or `"listing"`.
+  - `printingStyle`: The style to use to print the symbols, either `"csv"` or
+    `"listing"`.
   - TODO: port to Rust.
+- New `MapFile.fixupNonMatchingSymbols` method.
+  - Allows to fixup size calculation of symbols messed up by symbols with the
+    same name suffixed with `.NON_MATCHING`.
 
 ### Changed
 
diff --git a/src/mapfile_parser/frontends/jsonify.py b/src/mapfile_parser/frontends/jsonify.py
index 7b1a785..cf6493c 100644
--- a/src/mapfile_parser/frontends/jsonify.py
+++ b/src/mapfile_parser/frontends/jsonify.py
@@ -12,13 +12,15 @@
 from .. import mapfile
 
 
-def doJsonify(mapPath: Path, outputPath: Path|None, humanReadable: bool=True) -> int:
+def doJsonify(mapPath: Path, outputPath: Path|None, humanReadable: bool=True, applyFixes: bool=False) -> int:
     if not mapPath.exists():
         print(f"Could not find mapfile at '{mapPath}'")
         return 1
 
     mapFile = mapfile.MapFile()
     mapFile.readMapFile(mapPath)
+    if applyFixes:
+        mapFile = mapFile.fixupNonMatchingSymbols()
 
     jsonStr = json.dumps(mapFile.toJson(humanReadable=humanReadable), indent=4)
 
@@ -35,8 +37,9 @@ def processArguments(args: argparse.Namespace):
     mapPath: Path = args.mapfile
     outputPath: Path|None = Path(args.output) if args.output is not None else None
     machine: bool = args.machine
+    applyFixes: bool = args.applyFixes
 
-    exit(doJsonify(mapPath, outputPath, humanReadable=not machine))
+    exit(doJsonify(mapPath, outputPath, humanReadable=not machine, applyFixes=applyFixes))
 
 def addSubparser(subparser: argparse._SubParsersAction[argparse.ArgumentParser]):
     parser = subparser.add_parser("jsonify", help="Converts a mapfile into a json format.")
@@ -44,5 +47,6 @@ def addSubparser(subparser: argparse._SubParsersAction[argparse.ArgumentParser])
     parser.add_argument("mapfile", help="Path to a map file", type=Path)
     parser.add_argument("-o", "--output", help="Output path of for the generated json. If omitted then stdout is used instead.")
     parser.add_argument("-m", "--machine", help="Emit numbers as numbers instead of outputting them as pretty strings.", action="store_true")
+    parser.add_argument("-f", "--apply-fixes", help="Apply certain fixups, like fixing size calculation of because of the existence of fake `.NON_MATCHING` symbols.", action="store_true")
 
     parser.set_defaults(func=processArguments)
diff --git a/src/mapfile_parser/frontends/progress.py b/src/mapfile_parser/frontends/progress.py
index ab3326c..6c538bc 100644
--- a/src/mapfile_parser/frontends/progress.py
+++ b/src/mapfile_parser/frontends/progress.py
@@ -18,7 +18,7 @@ def getProgress(mapPath: Path, asmPath: Path, nonmatchingsPath: Path, pathIndex:
     mapFile.debugging = debugging
     mapFile.readMapFile(mapPath)
 
-    return mapFile.filterBySectionType(".text").getProgress(asmPath, nonmatchingsPath, pathIndex=pathIndex)
+    return mapFile.filterBySectionType(".text").fixupNonMatchingSymbols().getProgress(asmPath, nonmatchingsPath, pathIndex=pathIndex)
 
 def doProgress(mapPath: Path, asmPath: Path, nonmatchingsPath: Path, pathIndex: int=2, debugging: bool=False) -> int:
     if not mapPath.exists():
diff --git a/src/mapfile_parser/mapfile.py b/src/mapfile_parser/mapfile.py
index bae239e..1d588b7 100644
--- a/src/mapfile_parser/mapfile.py
+++ b/src/mapfile_parser/mapfile.py
@@ -146,6 +146,10 @@ def toJson(self, humanReadable: bool=True) -> dict[str, Any]:
         return result
 
 
+    def clone(self) -> Symbol:
+        return Symbol(self.name, self.vram, self.size, self.vrom, self.align)
+
+
     def __eq__(self, other: object) -> bool:
         if not isinstance(other, Symbol):
             return False
@@ -302,6 +306,13 @@ def appendSymbol(self, sym: Symbol) -> None:
         self._symbols.append(sym)
 
 
+    def clone(self) -> File:
+        f = File(self.filepath, self.vram, self.size, self.sectionType, self.vrom, self.align)
+        for sym in self._symbols:
+            f._symbols.append(sym.clone())
+        return f
+
+
     def __iter__(self) -> Generator[Symbol, None, None]:
         for sym in self._symbols:
             yield sym
@@ -476,6 +487,13 @@ def appendFile(self, file: File) -> None:
         self._filesList.append(file)
 
 
+    def clone(self) -> Segment:
+        s = Segment(self.name, self.vram, self.size, self.vrom, self.align)
+        for f in self._filesList:
+            s._filesList.append(f.clone())
+        return s
+
+
     def __iter__(self) -> Generator[File, None, None]:
         for file in self._filesList:
             yield file
@@ -672,6 +690,20 @@ def mixFolders(self) -> MapFile:
 
         return newMapFile
 
+    def fixupNonMatchingSymbols(self) -> MapFile:
+        newMapFile = self.clone()
+
+        for segment in newMapFile._segmentsList:
+            for file in segment._filesList:
+                for sym in file._symbols:
+                    if sym.name.endswith(".NON_MATCHING") and sym.size != 0:
+                        realSym = file.findSymbolByName(sym.name.replace(".NON_MATCHING", ""))
+                        if realSym is not None and realSym.size == 0:
+                            realSym.size = sym.size
+                            sym.size = 0
+
+        return newMapFile
+
     def getProgress(self, asmPath: Path, nonmatchings: Path, aliases: dict[str, str]=dict(), pathIndex: int=2) -> tuple[ProgressStats, dict[str, ProgressStats]]:
         totalStats = ProgressStats()
         progressPerFolder: dict[str, ProgressStats] = dict()
@@ -810,6 +842,14 @@ def appendSegment(self, segment: Segment) -> None:
         self._segmentsList.append(segment)
 
 
+    def clone(self) -> MapFile:
+        m = MapFile()
+        m.debugging = self.debugging
+        for s in self._segmentsList:
+            m._segmentsList.append(s.clone())
+        return m
+
+
     def __iter__(self) -> Generator[Segment, None, None]:
         for file in self._segmentsList:
             yield file
diff --git a/src/rs/file.rs b/src/rs/file.rs
index 2999aa1..46ed04f 100644
--- a/src/rs/file.rs
+++ b/src/rs/file.rs
@@ -62,6 +62,22 @@ impl File {
         self.symbols.iter().find(|&sym| sym.name == sym_name)
     }
 
+    pub fn find_symbol_and_index_by_name(
+        &self,
+        sym_name: &str,
+    ) -> Option<(&symbol::Symbol, usize)> {
+        for (index, sym) in self.symbols.iter().enumerate() {
+            if sym.name == sym_name {
+                return Some((sym, index));
+            }
+        }
+        None
+    }
+
+    pub fn find_symbol_by_name_mut(&mut self, sym_name: &str) -> Option<&mut symbol::Symbol> {
+        self.symbols.iter_mut().find(|sym| sym.name == sym_name)
+    }
+
     pub fn find_symbol_by_vram_or_vrom(&self, address: u64) -> Option<(&symbol::Symbol, i64)> {
         let mut prev_sym: Option<&symbol::Symbol> = None;
 
@@ -126,6 +142,29 @@ impl File {
         None
     }
 
+    pub fn fixup_non_matching_symbols(&mut self) {
+        let mut symbols_to_fix = Vec::new();
+
+        for (index, sym) in self.symbols.iter().enumerate() {
+            if sym.name.ends_with(".NON_MATCHING") && sym.size.is_some() && sym.size == Some(0) {
+                let real_name = sym.name.replace(".NON_MATCHING", "");
+
+                if let Some((_real_sym, real_index)) =
+                    self.find_symbol_and_index_by_name(&real_name)
+                {
+                    symbols_to_fix.push((real_index, sym.size));
+                    symbols_to_fix.push((index, Some(0)));
+                }
+            }
+        }
+
+        for (index, new_size) in symbols_to_fix {
+            if let Some(sym) = self.symbols.get_mut(index) {
+                sym.size = new_size;
+            }
+        }
+    }
+
     pub fn to_csv_header(print_vram: bool) -> String {
         let mut ret = String::new();
 
@@ -397,6 +436,10 @@ pub(crate) mod python_bindings {
             }
         }
 
+        fn fixupNonMatchingSymbols(&mut self) {
+            self.fixup_non_matching_symbols()
+        }
+
         #[staticmethod]
         #[pyo3(signature=(print_vram=true))]
         fn toCsvHeader(print_vram: bool) -> String {
diff --git a/src/rs/mapfile.rs b/src/rs/mapfile.rs
index fe40a82..e9d3e25 100644
--- a/src/rs/mapfile.rs
+++ b/src/rs/mapfile.rs
@@ -599,6 +599,17 @@ impl MapFile {
         new_map_file
     }
 
+    pub fn fixup_non_matching_symbols(&self) -> Self {
+        let mut new_map_file = self.clone();
+
+        new_map_file
+            .segments_list
+            .iter_mut()
+            .for_each(|x| x.fixup_non_matching_symbols());
+
+        new_map_file
+    }
+
     pub fn get_progress(
         &self,
         asm_path: &Path,
@@ -867,6 +878,10 @@ pub(crate) mod python_bindings {
             self.mix_folders()
         }
 
+        fn fixupNonMatchingSymbols(&self) -> Self {
+            self.fixup_non_matching_symbols()
+        }
+
         #[pyo3(signature = (asm_path, nonmatchings, aliases=HashMap::new(), path_index=2))]
         fn getProgress(
             &self,
diff --git a/src/rs/segment.rs b/src/rs/segment.rs
index 2137c72..9da83a7 100644
--- a/src/rs/segment.rs
+++ b/src/rs/segment.rs
@@ -156,6 +156,12 @@ impl Segment {
         new_segment
     }
 
+    pub fn fixup_non_matching_symbols(&mut self) {
+        self.files_list
+            .iter_mut()
+            .for_each(|x| x.fixup_non_matching_symbols())
+    }
+
     pub fn to_csv(&self, print_vram: bool, skip_without_symbols: bool) -> String {
         let mut ret = String::new();
 
@@ -385,6 +391,10 @@ pub(crate) mod python_bindings {
             self.mix_folders()
         }
 
+        fn fixupNonMatchingSymbols(&mut self) {
+            self.fixup_non_matching_symbols()
+        }
+
         #[pyo3(signature=(print_vram=true, skip_without_symbols=true))]
         fn toCsv(&self, print_vram: bool, skip_without_symbols: bool) -> String {
             self.to_csv(print_vram, skip_without_symbols)