diff --git a/m1/perf/sched.c b/m1/perf/sched.c
index 8a371d6..52ea00c 100644
--- a/m1/perf/sched.c
+++ b/m1/perf/sched.c
@@ -244,7 +244,7 @@ static int alloc_reg(struct insn *setter)
 	} else {
 		reg = list_pop(&sc->unallocated);
 		if (!reg)
-			abort();
+			return -1;
 
 		#ifdef REG_STATS
 		sc->curr_regs++;
@@ -495,10 +495,11 @@ static void unblock_after(struct insn *insn, int cycle)
 }
 
 
-static void issue(struct insn *insn, unsigned *code)
+static int issue(struct insn *insn, unsigned *code)
 {
 	struct data_ref *ref;
-	int end;
+	int end, reg;
+
 	end = sc->cycle+insn->latency;
 
 	Dprintf("cycle %d: insn %lu L %d (A %d B %d)\n", sc->cycle,
@@ -523,7 +524,10 @@ static void issue(struct insn *insn, unsigned *code)
 		abort();
 	}
 
-	CODE(end).dest = alloc_reg(insn);
+	reg = alloc_reg(insn);
+	if (reg < 0)
+		return -1;
+	CODE(end).dest = reg;
 	CODE(sc->cycle).opcode = fpvm_to_pfpu(insn->vm_insn->opcode);
 
 	foreach (ref, &insn->dependants)
@@ -580,7 +584,8 @@ static int schedule(unsigned int *code)
 			}
 		}
 		if (best) {
-			issue(best, code);
+			if (issue(best, code) < 0)
+				return -1;
 			list_del(&best->more);
 			remaining--;
 		}