diff --git a/check/fixes.frm b/check/fixes.frm
index ed00e021..265a7209 100644
--- a/check/fixes.frm
+++ b/check/fixes.frm
@@ -2285,3 +2285,15 @@ Print +s;
 assert succeeded?
 assert result("F3") =~ expr("+D")
 *--#] Issue405 :
+*--#[ Issue434 :
+* Memory error with macros with arguments
+* The loop (appending a variable and calling the macro) is repeated enough
+* to hit the problem (Valgrind error).
+#define var(a) "`~a'"
+#do n=1,{12*2^5}
+  #define x
+  #message `var(`n')'
+#enddo
+.end
+assert succeeded?
+*--#] Issue434 :
diff --git a/sources/pre.c b/sources/pre.c
index b6697201..6aa45bf4 100644
--- a/sources/pre.c
+++ b/sources/pre.c
@@ -310,6 +310,7 @@ UBYTE GetChar(int level)
 */
 					int nargs = 1;
 					PREVAR *p;
+					size_t p_offset;
 					*s++ = 0; namebuf[i-2] = 0;
 					if ( StrICmp(namebuf,(UBYTE *)"random_") == 0 ) {
 						UBYTE *ranvalue;
@@ -367,6 +368,7 @@ UBYTE GetChar(int level)
 					while ( *s ) s++;
 					s++;
 					t = p->argnames;
+					p_offset = p - PreVar;
 					for ( j = 0; j < p->nargs; j++ ) {
 						if ( ( nargs == p->nargs-1 ) && ( *t == '?' ) ) {
 							PutPreVar(t,0,0,0);
@@ -376,6 +378,7 @@ UBYTE GetChar(int level)
 							while ( *s ) s++;
 							s++;
 						}
+						p = PreVar + p_offset;
 						while ( *t ) t++;
 						t++;
 					}