Index: ext/misc/csv.c
==================================================================
--- ext/misc/csv.c
+++ ext/misc/csv.c
@@ -76,11 +76,11 @@
   char *z;               /* Accumulated text for a field */
   int n;                 /* Number of bytes in z */
   int nAlloc;            /* Space allocated for z[] */
   int nLine;             /* Current line number */
   int bNotFirst;         /* True if prior text has been seen */
-  char cTerm;            /* Character that terminated the most recent field */
+  int cTerm;             /* Character that terminated the most recent field */
   size_t iIn;            /* Next unread character in the input buffer */
   size_t nIn;            /* Number of characters in the input buffer */
   char *zIn;             /* The input buffer */
   char zErr[CSV_MXERR];  /* Error message */
 };
@@ -164,11 +164,11 @@
 static int csv_getc(CsvReader *p){
   if( p->iIn >= p->nIn ){
     if( p->in!=0 ) return csv_getc_refill(p);
     return EOF;
   }
-  return p->zIn[p->iIn++];
+  return ((unsigned char*)p->zIn)[p->iIn++];
 }
 
 /* Increase the size of p->z and append character c to the end. 
 ** Return 0 on success and non-zero if there is an OOM error */
 static CSV_NOINLINE int csv_resize_and_append(CsvReader *p, char c){

Index: test/releasetest.tcl
==================================================================
--- test/releasetest.tcl
+++ test/releasetest.tcl
@@ -112,11 +112,11 @@
     -DSQLITE_ENABLE_STMT_SCANSTATUS
     --enable-json1 --enable-fts5 --enable-session
   }
   "Debug-One" {
     --disable-shared
-    -O2
+    -O2 -funsigned-char
     -DSQLITE_DEBUG=1
     -DSQLITE_MEMDEBUG=1
     -DSQLITE_MUTEX_NOOP=1
     -DSQLITE_TCL_DEFAULT_FULLMUTEX=1
     -DSQLITE_ENABLE_FTS3=1