diff --git a/sys/src/cmd/dtracy/act.c b/sys/src/cmd/dtracy/act.c
index dde47ae57..2159ce19e 100644
--- a/sys/src/cmd/dtracy/act.c
+++ b/sys/src/cmd/dtracy/act.c
@@ -192,7 +192,8 @@ prepprintf(Node **arg, int narg, DTActGr *g, int *recoff)
 			goto again;
 		case 'x': case 'X': case 'o': case 'b': case 'd':
 			if(n >= narg) sysfatal("printf() too few arguments");
-			if(arg[n]->typ->type != TYPINT) sysfatal("print() %%%c with non-integer", *fmt);
+			if(arg[n]->typ->type != TYPINT)
+				sysfatal("%d: print() %%%c with non-integer", arg[n]->line, *fmt);
 			arg[n] = tracegen(arg[n], g, recoff);
 			n++;
 			fmtrune(&f, 'l');
@@ -201,7 +202,8 @@ prepprintf(Node **arg, int narg, DTActGr *g, int *recoff)
 			break;
 		case 's':
 			if(n >= narg) sysfatal("printf() too few arguments");
-			if(arg[n]->typ->type != TYPSTRING) sysfatal("print() %%s with non-string");
+			if(arg[n]->typ->type != TYPSTRING)
+				sysfatal("%d: print() %%s with non-string", arg[n]->line);
 			arg[n] = tracegen(arg[n], g, recoff);
 			n++;
 			fmtrune(&f, *fmt);
diff --git a/sys/src/cmd/dtracy/dat.h b/sys/src/cmd/dtracy/dat.h
index 5087a609e..cffc1968b 100644
--- a/sys/src/cmd/dtracy/dat.h
+++ b/sys/src/cmd/dtracy/dat.h
@@ -75,6 +75,7 @@ struct Node {
 	Symbol *sym;
 	char *str;
 	s64int num;
+	int line;
 	
 	/* used by elidecasts() */
 	char databits;
diff --git a/sys/src/cmd/dtracy/lex.c b/sys/src/cmd/dtracy/lex.c
index c820f145c..bd7825542 100644
--- a/sys/src/cmd/dtracy/lex.c
+++ b/sys/src/cmd/dtracy/lex.c
@@ -239,6 +239,7 @@ node(int type, ...)
 	
 	n = emalloc(sizeof(Node));
 	n->type = type;
+	n->line = lineno;
 	va_start(va, type);
 	switch(type){
 	case OBIN: