diff --git a/arm9/source/filesys/filetype.h b/arm9/source/filesys/filetype.h
index a6ecad1..64e57a7 100644
--- a/arm9/source/filesys/filetype.h
+++ b/arm9/source/filesys/filetype.h
@@ -53,6 +53,7 @@
 #define FTYPE_KEYBUILD(tp)      (tp&(BIN_KEYDB|BIN_LEGKEY))
 #define FTYPE_TITLEINFO(tp)     (tp&(GAME_SMDH|GAME_NCCH|GAME_NCSD|GAME_CIA|GAME_TMD|GAME_NDS|GAME_GBA|GAME_TAD|GAME_3DSX))
 #define FTYPE_RENAMABLE(tp)     (tp&(GAME_NCCH|GAME_NCSD|GAME_CIA|GAME_NDS|GAME_GBA))
+#define FTYPE_TRIMABLE(tp)      (tp&(IMG_NAND|GAME_NCCH|GAME_NCSD|GAME_NDS|SYS_FIRM))
 #define FTYPE_TRANSFERABLE(tp)  ((u64) (tp&(IMG_FAT|FLAG_CTR)) == (u64) (IMG_FAT|FLAG_CTR))
 #define FTYPE_NCSDFIXABLE(tp)   (tp&(HDR_NAND|NOIMG_NAND))
 #define FTYPE_HASCODE(tp)       (((u64) (tp&(GAME_NCCH|FLAG_CXI)) == (u64) (GAME_NCCH|FLAG_CXI))|(tp&GAME_NCSD))
diff --git a/arm9/source/filesys/vff.c b/arm9/source/filesys/vff.c
index dc97116..70a9c91 100644
--- a/arm9/source/filesys/vff.c
+++ b/arm9/source/filesys/vff.c
@@ -1,4 +1,3 @@
-#include "sddata.h"
 #include "virtual.h"
 #include "ffconf.h"
 #include "vff.h"
diff --git a/arm9/source/filesys/vff.h b/arm9/source/filesys/vff.h
index 0fa1e6b..17ebe8d 100644
--- a/arm9/source/filesys/vff.h
+++ b/arm9/source/filesys/vff.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "common.h"
+#include "sddata.h"
 #include "ff.h"
 
 #define AM_VRT 0x40 // Virtual (FILINFO FAT attribute)
diff --git a/arm9/source/godmode.c b/arm9/source/godmode.c
index f0fa11e..63486ab 100644
--- a/arm9/source/godmode.c
+++ b/arm9/source/godmode.c
@@ -1029,6 +1029,8 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
     bool key_buildable = (FTYPE_KEYBUILD(filetype)) && !in_output_path && !((drvtype & DRV_VIRTUAL) && (drvtype & DRV_SYSNAND));
     bool titleinfo = (FTYPE_TITLEINFO(filetype));
     bool renamable = (FTYPE_RENAMABLE(filetype));
+    bool trimable = (FTYPE_TRIMABLE(filetype)) && !(drvtype & DRV_VIRTUAL) && !(drvtype & DRV_ALIAS) &&
+        !(drvtype & DRV_CTRNAND) && !(drvtype & DRV_TWLNAND) && !(drvtype & DRV_IMAGE);
     bool transferable = (FTYPE_TRANSFERABLE(filetype) && IS_A9LH && (drvtype & DRV_FAT));
     bool hsinjectable = (FTYPE_HASCODE(filetype));
     bool extrcodeable = (FTYPE_HASCODE(filetype));
@@ -1056,7 +1058,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
         extrcodeable = (FTYPE_HASCODE(filetype_cxi));
     }
     
-    bool special_opt = mountable || verificable || decryptable || encryptable || cia_buildable || cia_buildable_legit || cxi_dumpable || tik_buildable || key_buildable || titleinfo || renamable || transferable || hsinjectable || restorable || xorpadable || ebackupable || ncsdfixable || extrcodeable || extrdiffable || keyinitable || keyinstallable || bootable || scriptable || fontable || viewable || installable || agbexportable || agbimportable;
+    bool special_opt = mountable || verificable || decryptable || encryptable || cia_buildable || cia_buildable_legit || cxi_dumpable || tik_buildable || key_buildable || titleinfo || renamable || trimable || transferable || hsinjectable || restorable || xorpadable || ebackupable || ncsdfixable || extrcodeable || extrdiffable || keyinitable || keyinstallable || bootable || scriptable || fontable || viewable || installable || agbexportable || agbimportable;
     
     char pathstr[32+1];
     TruncateString(pathstr, file_path, 32, 8);
@@ -1244,6 +1246,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
     int hsinject = (hsinjectable) ? ++n_opt : -1;
     int extrcode = (extrcodeable) ? ++n_opt : -1;
     int extrdiff = (extrdiffable) ? ++n_opt : -1;
+    int trim = (trimable) ? ++n_opt : -1;
     int rename = (renamable) ? ++n_opt : -1;
     int xorpad = (xorpadable) ? ++n_opt : -1;
     int xorpad_inplace = (xorpadable) ? ++n_opt : -1;
@@ -1272,6 +1275,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
     if (verify > 0) optionstr[verify-1] = "Verify file";
     if (ctrtransfer > 0) optionstr[ctrtransfer-1] = "Transfer image to CTRNAND";
     if (hsinject > 0) optionstr[hsinject-1] = "Inject to H&S";
+    if (trim > 0) optionstr[trim-1] = "Trim file";
     if (rename > 0) optionstr[rename-1] = "Rename file";
     if (xorpad > 0) optionstr[xorpad-1] = "Build XORpads (SD output)";
     if (xorpad_inplace > 0) optionstr[xorpad_inplace-1] = "Build XORpads (inplace)";
@@ -1556,6 +1560,30 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
             (BuildKeyDb(file_path, true) == 0) ? "success" : "failed");
         return 0;
     }
+    else if (user_select == trim) { // -> Game file trimmer
+        u64 trimsize = GetGameFileTrimmedSize(file_path);
+        u64 currentsize = FileGetSize(file_path);
+        char tsizestr[32];
+        char csizestr[32];
+        char dsizestr[32];
+        FormatBytes(tsizestr, trimsize);
+        FormatBytes(csizestr, currentsize);
+        FormatBytes(dsizestr, currentsize - trimsize);
+
+        if (!trimsize || trimsize > currentsize) {
+            ShowPrompt(false, "%s\nFile can't be trimmed.", pathstr);
+        } else if (trimsize == currentsize) {
+            ShowPrompt(false, "%s\nFile is already trimmed.", pathstr);
+        } else if (ShowPrompt(true, "%s\nCurrent size: %s\nTrimmed size: %s\nDifference: %s\n \nTrim this file?",
+            pathstr, csizestr, tsizestr, dsizestr)) {
+            if (TrimGameFile(file_path) != 0) ShowPrompt(false, "%s\nTrimming failed.", pathstr);
+            else {
+                ShowPrompt(false, "%s\nTrimmed by %s.", pathstr, dsizestr);
+                GetDirContents(current_dir, current_path);
+            }
+        }
+        return 0;
+    }
     else if (user_select == rename) { // -> Game file renamer
         if ((n_marked > 1) && ShowPrompt(true, "Try to rename all %lu selected files?", n_marked)) {
             u32 n_success = 0;
diff --git a/arm9/source/utils/gameutil.c b/arm9/source/utils/gameutil.c
index efbde7f..557b8c8 100644
--- a/arm9/source/utils/gameutil.c
+++ b/arm9/source/utils/gameutil.c
@@ -1,6 +1,7 @@
 #include "gameutil.h"
 #include "disadiff.h"
 #include "game.h"
+#include "nand.h" // so that we can trim NAND images
 #include "hid.h"
 #include "ui.h"
 #include "fs.h"
@@ -1654,6 +1655,56 @@ u32 ExtractDataFromDisaDiff(const char* path) {
     return ret;
 }
 
+u64 GetGameFileTrimmedSize(const char* path) {
+    u64 filetype = IdentifyFileType(path);
+    u64 trimsize = 0;
+
+    if (filetype & GAME_NDS) {
+        TwlHeader hdr;
+        if (fvx_qread(path, &hdr, 0, sizeof(TwlHeader), NULL) != FR_OK)
+            return 0;
+        if (hdr.unit_code != 0x00) // DSi or NDS+DSi
+            trimsize = hdr.ntr_twl_rom_size;
+        else trimsize = hdr.ntr_rom_size; // regular NDS
+    } else {
+        u8 hdr[0x200];
+        if (fvx_qread(path, &hdr, 0, 0x200, NULL) != FR_OK)
+            return 0;
+        if (filetype & IMG_NAND)
+            trimsize = GetNandNcsdMinSizeSectors((NandNcsdHeader*) (void*) hdr) * 0x200;
+        else if (filetype & SYS_FIRM)
+            trimsize = GetFirmSize((FirmHeader*) (void*) hdr);
+        else if (filetype & GAME_NCSD)
+            trimsize = GetNcsdTrimmedSize((NcsdHeader*) (void*) hdr);
+        else if (filetype & GAME_NCCH)
+            trimsize = ((NcchHeader*) (void*) hdr)->size * NCCH_MEDIA_UNIT;
+    }
+
+    // safety check for file size
+    if (trimsize > fvx_qsize(path))
+        trimsize = 0;
+
+    return trimsize;
+}
+
+u32 TrimGameFile(const char* path) {
+    u64 trimsize = GetGameFileTrimmedSize(path);
+    if (!trimsize) return 1;
+
+    // actual truncate routine - FAT only
+    FIL fp;
+    if (fx_open(&fp, path, FA_WRITE | FA_OPEN_EXISTING) != FR_OK)
+        return 1;
+    if ((f_lseek(&fp, (u32) trimsize) != FR_OK) || (f_truncate(&fp) != FR_OK)) {
+        fx_close(&fp);
+        return 1;
+    }
+    fx_close(&fp);
+
+    // all done
+    return 0;
+}
+
 u32 LoadSmdhFromGameFile(const char* path, Smdh* smdh) {
     u64 filetype = IdentifyFileType(path);
     
diff --git a/arm9/source/utils/gameutil.h b/arm9/source/utils/gameutil.h
index 25e0f37..5d28d67 100644
--- a/arm9/source/utils/gameutil.h
+++ b/arm9/source/utils/gameutil.h
@@ -9,6 +9,8 @@ u32 BuildCiaFromGameFile(const char* path, bool force_legit);
 u32 DumpCxiSrlFromTmdFile(const char* path);
 u32 ExtractCodeFromCxiFile(const char* path, const char* path_out, char* extstr);
 u32 ExtractDataFromDisaDiff(const char* path);
+u64 GetGameFileTrimmedSize(const char* path);
+u32 TrimGameFile(const char* path);
 u32 ShowGameFileTitleInfo(const char* path);
 u32 GetTmdContentPath(char* path_content, const char* path_tmd);
 u32 BuildNcchInfoXorpads(const char* destdir, const char* path);