diff --git a/src/interfaces/ecpg/preproc/pgc.l b/src/interfaces/ecpg/preproc/pgc.l
index 283343d8228..3601544da20 100644
--- a/src/interfaces/ecpg/preproc/pgc.l
+++ b/src/interfaces/ecpg/preproc/pgc.l
@@ -566,6 +566,7 @@ cppline			{space}*#([^i][A-Za-z]*|{if}|{ifdef}|{ifndef}|{import})((\/\*[^*/]*\*+
 				{
 					addlit(yytext, yyleng);
 					free(dolqstart);
+					dolqstart = NULL;
 					BEGIN(SQL);
 					base_yylval.str = mm_strdup(literalbuf);
 					return DOLCONST;