diff --git a/port/src/romdata.c b/port/src/romdata.c
index 08629ecf4..effc67e65 100644
--- a/port/src/romdata.c
+++ b/port/src/romdata.c
@@ -64,6 +64,13 @@ enum loadsource {
 	SRC_EXTERNAL
 };
 
+struct romfilepatch {
+	u32 ofs;
+	u32 len;
+	const char *src;
+	const char *dst;
+};
+
 struct romfile {
 	u8 **segstart;
 	u8 **segend;
@@ -73,9 +80,21 @@ struct romfile {
 	preprocessfunc preprocess;
 	s32 source; // enum loadsource
 	s32 preprocessed;
+	const struct romfilepatch *patches;
+	u32 numpatches;
 };
 
-static struct romfile fileSlots[ROMDATA_MAX_FILES];
+/* patches for individual files; applied on file load, before preprocFuncs, but */
+/* after unzip; only applied when loading from a ROM file                       */
+static const struct romfilepatch filePatches[] = {
+	/* FILE_USETUPLUE: fixes Jon's double "if what" in Infiltration outro */
+	{ 0x92a2, 1, "\x6c", "\x99" },
+	{ 0x92b0, 1, "\x6c", "\x99" },
+};
+
+static struct romfile fileSlots[ROMDATA_MAX_FILES] = {
+	[FILE_USETUPLUE] = { .patches = &filePatches[0], .numpatches = 2 },
+};
 
 #define ROMSEG_START(n) _ ## n ## SegmentRomStart
 #define ROMSEG_END(n) _ ## n ## SegmentRomEnd
@@ -409,6 +428,8 @@ u8 *romdataFileLoad(s32 fileNum, u32 *outSize)
 				fileSlots[fileNum].data = out;
 				fileSlots[fileNum].size = size;
 				fileSlots[fileNum].source = SRC_EXTERNAL;
+				// external file; do not apply patches to this
+				fileSlots[fileNum].numpatches = 0;
 			}
 		}
 		// tried and failed, fall back to ROM
@@ -435,6 +456,15 @@ void romdataFilePreprocess(s32 fileNum, s32 loadType, u8 *data, u32 size)
 
 	if (data && size /* && !fileSlots[fileNum].preprocessed*/) {
 		if (loadType && loadType < (u32)ARRAYCOUNT(filePreprocFuncs) && filePreprocFuncs[loadType]) {
+			// apply patches
+			for (u32 i = 0; i < fileSlots[fileNum].numpatches; ++i) {
+				const struct romfilepatch *p = &fileSlots[fileNum].patches[i];
+				if (!memcmp(data + p->ofs, p->src, p->len)) {
+					memcpy(data + p->ofs, p->dst, p->len);
+					sysLogPrintf(LOG_NOTE, "file %d (%s) patched at offset 0x%x", fileNum, fileSlots[fileNum].name, p->ofs);
+				}
+			}
+			// then preprocess
 			filePreprocFuncs[loadType](data, size);
 			// fileSlots[fileNum].preprocessed = 1;
 		}