diff --git a/ext/fts3/fts3Int.h b/ext/fts3/fts3Int.h
index 06f3c6efec..a53ecdf17c 100644
--- a/ext/fts3/fts3Int.h
+++ b/ext/fts3/fts3Int.h
@@ -202,6 +202,19 @@ typedef sqlite3_int64 i64;        /* 8-byte signed integer */
 
 #define deliberate_fall_through
 
+/*
+** Macros needed to provide flexible arrays in a portable way
+*/
+#ifndef offsetof
+# define offsetof(STRUCTURE,FIELD) ((size_t)((char*)&((STRUCTURE*)0)->FIELD))
+#endif
+#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
+# define FLEXARRAY
+#else
+# define FLEXARRAY 1
+#endif
+
+
 #endif /* SQLITE_AMALGAMATION */
 
 #ifdef SQLITE_DEBUG
@@ -431,9 +444,13 @@ struct Fts3Phrase {
   */
   int nToken;                /* Number of tokens in the phrase */
   int iColumn;               /* Index of column this phrase must match */
-  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */
+  Fts3PhraseToken aToken[FLEXARRAY]; /* One for each token in the phrase */
 };
 
+/* Size (in bytes) of an Fts3Phrase object large enough to hold N tokens */
+#define SZ_FTS3PHRASE(N) \
+  (offsetof(Fts3Phrase,aToken)+(N)*sizeof(Fts3PhraseToken))
+
 /*
 ** A tree of these objects forms the RHS of a MATCH operator.
 **
diff --git a/ext/fts3/fts3_expr.c b/ext/fts3/fts3_expr.c
index ca857835e2..55943c271f 100644
--- a/ext/fts3/fts3_expr.c
+++ b/ext/fts3/fts3_expr.c
@@ -202,7 +202,7 @@ static int getNextToken(
 
     rc = pModule->xNext(pCursor, &zToken, &nToken, &iStart, &iEnd, &iPosition);
     if( rc==SQLITE_OK ){
-      nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase) + nToken;
+      nByte = sizeof(Fts3Expr) + SZ_FTS3PHRASE(1) + nToken;
       pRet = (Fts3Expr *)sqlite3Fts3MallocZero(nByte);
       if( !pRet ){
         rc = SQLITE_NOMEM;
@@ -212,7 +212,7 @@ static int getNextToken(
         pRet->pPhrase->nToken = 1;
         pRet->pPhrase->iColumn = iCol;
         pRet->pPhrase->aToken[0].n = nToken;
-        pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
+        pRet->pPhrase->aToken[0].z = (char*)&pRet->pPhrase->aToken[1];
         memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);
 
         if( iEnd<n && z[iEnd]=='*' ){
@@ -285,7 +285,7 @@ static int getNextString(
   char *zTemp = 0;
   i64 nTemp = 0;
 
-  const int nSpace = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
+  const int nSpace = sizeof(Fts3Expr) + SZ_FTS3PHRASE(1);
   int nToken = 0;
 
   /* The final Fts3Expr data structure, including the Fts3Phrase,
diff --git a/ext/fts3/fts3_snippet.c b/ext/fts3/fts3_snippet.c
index 9ec7df3802..5272d46bf0 100644
--- a/ext/fts3/fts3_snippet.c
+++ b/ext/fts3/fts3_snippet.c
@@ -111,6 +111,10 @@ struct MatchinfoBuffer {
   u32 aMatchinfo[1];
 };
 
+/* Size (in bytes) of a MatchinfoBuffer sufficient for N elements */
+#define SZ_MATCHINFOBUFFER(N) \
+            (offsetof(MatchinfoBuffer,aMatchinfo)+((((N)+1)/2)*sizeof(u64))
+
 
 /*
 ** The snippet() and offsets() functions both return text values. An instance
diff --git a/manifest b/manifest
index 2e3a0d5c67..999dcec3d4 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Use\sflexible\sarrays\sfor\sRTREE.
-D 2025-03-14T20:19:49.223
+C Fix\sone\sof\stwo\sflexible\sarrays\sin\sFTS3.
+D 2025-03-14T21:15:11.288
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md e108e1e69ae8e8a59e93c455654b8ac9356a11720d3345df2a4743e9590fb20d
@@ -80,14 +80,14 @@ F ext/fts3/README.tokenizers b92bdeb8b46503f0dd301d364efc5ef59ef9fa8e2758b8e742f
 F ext/fts3/README.txt 8c18f41574404623b76917b9da66fcb0ab38328d
 F ext/fts3/fts3.c fd2a8642fa4701ef5dd6bce7947ecb3c7ae472e1d44022772454a8b74a13155d
 F ext/fts3/fts3.h 3a10a0af180d502cecc50df77b1b22df142817fe
-F ext/fts3/fts3Int.h 75b9cf37c93d3c56d8e569d64527c927cb54a5279afb3823740ca1e29e481c15
+F ext/fts3/fts3Int.h ad51347fa5a5a49f6c3bd40a961eafd08f1e410f60b64dea06f115697a2ad9fe
 F ext/fts3/fts3_aux.c 7eab82a9cf0830f6551ba3abfdbe73ed39e322a4d3940ee82fbf723674ecd9f3
-F ext/fts3/fts3_expr.c 673bf600655f5080239ff0e1e80eaae0176389f7e7d3af54c6d51491280ca360
+F ext/fts3/fts3_expr.c 8a20522514c6e93c2935e90b7d269a8819111a6a17a5a91513cd4efcc37c1757
 F ext/fts3/fts3_hash.c d9dba473741445789330c7513d4f65737c92df23c3212784312931641814672a
 F ext/fts3/fts3_hash.h 39cf6874dc239d6b4e30479b1975fe5b22a3caaf
 F ext/fts3/fts3_icu.c 305ce7fb6036484085b5556a9c8e62acdc7763f0f4cdf5fd538212a9f3720116
 F ext/fts3/fts3_porter.c 024417020c57dd1ab39816f5fe6cf45222a857b78a1f6412f040ada1ceabd4ff
-F ext/fts3/fts3_snippet.c ac402ba81ce9503a54238f975d870384f8b9fb3680f6b86eb7a1be44829a1cee
+F ext/fts3/fts3_snippet.c 53cb456dbf7f1cfed57f031bf94efc5df7bcd20158fb0442f891879f3b9337f8
 F ext/fts3/fts3_term.c 6a96027ad364001432545fe43322b6af04ed28bb5619ec51af1f59d0710d6d69
 F ext/fts3/fts3_test.c 7a9cb3d61774134211bf4bfdf1adcb581a1a0377f2d050a121ae7ab44baef0e3
 F ext/fts3/fts3_tokenize_vtab.c 7fd9ef364f257b97218b9c331f2378e307375c592f70fd541f714e747d944962
@@ -2213,8 +2213,8 @@ F tool/version-info.c 3b36468a90faf1bbd59c65fd0eb66522d9f941eedd364fabccd7227350
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
 F tool/warnings.sh 49a486c5069de041aedcbde4de178293e0463ae9918ecad7539eedf0ec77a139
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 37b687dc2d3b9dc82ed09a9c5b2c00e576b1eebe358a20d18a3da190347b644e
-R c3a6881fe54f628cb6eebb7a30e7280b
+P 2b41776179c726586e3ff836edcf235938cf02f7c5e33c1d6954b84d4061b8d5
+R b928acd4f3ec564994a518332f83b638
 U drh
-Z 9b83357076de4b4a7589bb4979f7b8b7
+Z f48ebbbdb7fe4570c0fe613e575ace55
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index dae93f569a..a4f78c7437 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-2b41776179c726586e3ff836edcf235938cf02f7c5e33c1d6954b84d4061b8d5
+ddfa87c17906ecf7fd5639a87bbfa9a87d17ab688159acd2fd80cc5b6f25f09b