Index: src/printf.c
==================================================================
--- src/printf.c
+++ src/printf.c
@@ -3,11 +3,11 @@
 ** the public domain.  The original comments are included here for
 ** completeness.  They are very out-of-date but might be useful as
 ** an historical reference.  Most of the "enhancements" have been backed
 ** out so that the functionality is now the same as standard printf().
 **
-** $Id: printf.c,v 1.96 2008/11/20 18:20:28 drh Exp $
+** $Id: printf.c,v 1.97 2008/11/22 18:28:51 drh Exp $
 **
 **************************************************************************
 **
 ** The following modules is an enhanced replacement for the "printf" subroutines
 ** found in the standard C library.  The following enhancements are
@@ -723,11 +723,11 @@
     return;
   }
   if( N<0 ){
     N = strlen(z);
   }
-  if( N==0 ){
+  if( N==0 || z==0 ){
     return;
   }
   if( p->nChar+N >= p->nAlloc ){
     char *zNew;
     if( !p->useMalloc ){

ADDED   test/tkt3508.test
Index: test/tkt3508.test
==================================================================
--- /dev/null
+++ test/tkt3508.test
@@ -0,0 +1,38 @@
+# 2008 November 22
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library. 
+#
+# $Id: tkt3508.test,v 1.1 2008/11/22 18:28:51 drh Exp $
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+do_test tkt3508-1.1 {
+  execsql {
+    CREATE TABLE modificationsTmp (
+      SUBSTRATE_HPRD_ID VARCHAR(80),
+      SUBSTRATE_GENE_SYMBOL VARCHAR(80),
+      SUBSTRATE_ISOFORM_ID VARCHAR(80),
+      SUBSTRATE_REFSEQ_ID VARCHAR(80),
+      SITE INTEGER,
+      RESIDUE VARCHAR(80),
+      ENZYME_NAME VARCHAR(80),
+      ENZYME_HPRD_ID VARCHAR(80),
+      MODIFICATION_TYPE VARCHAR(80),
+      EXPERIMENT_TYPE VARCHAR(80),
+      REFERENCE_ID VARCHAR(80)
+    );
+    select SUBSTRATE_HPRD_ID, count(substrate_refseq_id) as c
+      from modificationsTmp where c > 1 group by SUBSTRATE_HPRD_ID;
+  }
+} {}
+
+finish_test