diff -Nru /n/sources/plan9/sys/src/cmd/cc/cc.y /sys/src/cmd/cc/cc.y
--- /n/sources/plan9/sys/src/cmd/cc/cc.y	Tue Apr 23 23:19:24 2013
+++ /sys/src/cmd/cc/cc.y	Sun Nov  6 00:00:00 2016
@@ -1008,7 +1008,7 @@
 |	LSTRUCT sbody
 	{
 		taggen++;
-		sprint(symb, "_%d_", taggen);
+		snprint(symb, sizeof symb, "_%d_", taggen);
 		$$ = dotag(lookup(), TSTRUCT, autobn);
 		$$->link = $2;
 		sualign($$);
@@ -1033,7 +1033,7 @@
 |	LUNION sbody
 	{
 		taggen++;
-		sprint(symb, "_%d_", taggen);
+		snprint(symb, sizeof symb, "_%d_", taggen);
 		$$ = dotag(lookup(), TUNION, autobn);
 		$$->link = $2;
 		sualign($$);
diff -Nru /n/sources/plan9/sys/src/cmd/cc/funct.c /sys/src/cmd/cc/funct.c
--- /n/sources/plan9/sys/src/cmd/cc/funct.c	Sun Mar  2 23:10:19 2014
+++ /sys/src/cmd/cc/funct.c	Sun Nov  6 00:00:00 2016
@@ -262,7 +262,7 @@
 		o = ftabinit[i].op;
 		if(o == OXXX)
 			break;
-		sprint(str, "%s_%s_", t->tag->name, ftabinit[i].name);
+		snprint(str, sizeof str, "%s_%s_", t->tag->name, ftabinit[i].name);
 		n = new(ONAME, Z, Z);
 		n->sym = slookup(str);
 		f->sym[o] = n->sym;
@@ -296,7 +296,7 @@
 		/*
 		 * OCAST types T1 _T2_T1_(T2)
 		 */
-		sprint(str, "_%s%s_", gtabinit[i].name, t->tag->name);
+		snprint(str, sizeof str, "_%s%s_", gtabinit[i].name, t->tag->name);
 		n = new(ONAME, Z, Z);
 		n->sym = slookup(str);
 		f->castto[o] = n->sym;
@@ -305,7 +305,7 @@
 		f1->down = types[o];
 		dodecl(xdecl, CEXTERN, f1, n);
 
-		sprint(str, "%s_%s_", t->tag->name, gtabinit[i].name);
+		snprint(str, sizeof str, "%s_%s_", t->tag->name, gtabinit[i].name);
 		n = new(ONAME, Z, Z);
 		n->sym = slookup(str);
 		f->castfr[o] = n->sym;
diff -Nru /n/sources/plan9/sys/src/cmd/cc/lex.c /sys/src/cmd/cc/lex.c
--- /n/sources/plan9/sys/src/cmd/cc/lex.c	Fri Aug  2 20:36:13 2013
+++ /sys/src/cmd/cc/lex.c	Sun Nov  6 00:00:00 2016
@@ -258,11 +258,11 @@
 			/* 1999 ANSI C requires recognising // comments */
 			av[i++] = strdup("-+");
 			for(c = 0; c < ndef; c++) {
-				sprint(opt, "-D%s", defs[c]);
+				snprint(opt, sizeof opt, "-D%s", defs[c]);
 				av[i++] = strdup(opt);
 			}
 			for(c = 0; c < ninclude; c++) {
-				sprint(opt, "-I%s", include[c]);
+				snprint(opt, sizeof opt, "-I%s", include[c]);
 				av[i++] = strdup(opt);
 			}
 			if(strcmp(file, "stdin") != 0)
@@ -1386,19 +1386,19 @@
 		if(str[0])
 			strcat(str, " ");
 		if(t->garb&~GINCOMPLETE) {
-			sprint(s, "%s ", gnames[t->garb&~GINCOMPLETE]);
+			snprint(s, sizeof s, "%s ", gnames[t->garb&~GINCOMPLETE]);
 			if(strlen(str) + strlen(s) < STRINGSZ)
 				strcat(str, s);
 		}
-		sprint(s, "%s", tnames[et]);
+		snprint(s, sizeof s, "%s", tnames[et]);
 		if(strlen(str) + strlen(s) < STRINGSZ)
 			strcat(str, s);
 		if(et == TFUNC && (t1 = t->down)) {
-			sprint(s, "(%T", t1);
+			snprint(s, sizeof s, "(%T", t1);
 			if(strlen(str) + strlen(s) < STRINGSZ)
 				strcat(str, s);
 			while(t1 = t1->down) {
-				sprint(s, ", %T", t1);
+				snprint(s, sizeof s, ", %T", t1);
 				if(strlen(str) + strlen(s) < STRINGSZ)
 					strcat(str, s);
 			}
@@ -1409,12 +1409,12 @@
 			n = t->width;
 			if(t->link && t->link->width)
 				n /= t->link->width;
-			sprint(s, "[%ld]", n);
+			snprint(s, sizeof s, "[%ld]", n);
 			if(strlen(str) + strlen(s) < STRINGSZ)
 				strcat(str, s);
 		}
 		if(t->nbits) {
-			sprint(s, " %d:%d", t->shift, t->nbits);
+			snprint(s, sizeof s, " %d:%d", t->shift, t->nbits);
 			if(strlen(str) + strlen(s) < STRINGSZ)
 				strcat(str, s);
 		}