diff --git a/lib/libc/stdlib/qsort.c b/lib/libc/stdlib/qsort.c
--- a/lib/libc/stdlib/qsort.c
+++ b/lib/libc/stdlib/qsort.c
@@ -91,41 +91,23 @@
 	      :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
 }
 
+/*
+ * The actual qsort() implementation is static to avoid preemptible calls when
+ * recursing. Also give them different names for improved debugging.
+ */
 #if defined(I_AM_QSORT_R)
-void
-qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
+#define local_qsort local_qsort_r
 #elif defined(I_AM_QSORT_S)
-errno_t
-qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
-#else
-#define	thunk NULL
-void
-qsort(void *a, size_t n, size_t es, cmp_t *cmp)
+#define local_qsort local_qsort_s
 #endif
+static void
+local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
 {
 	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 	size_t d1, d2;
 	int cmp_result;
 	int swap_cnt;
 
-#ifdef I_AM_QSORT_S
-	if (n > RSIZE_MAX) {
-		__throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
-		return (EINVAL);
-	} else if (es > RSIZE_MAX) {
-		__throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", EINVAL);
-		return (EINVAL);
-	} else if (n != 0) {
-		if (a == NULL) {
-			__throw_constraint_handler_s("qsort_s : a == NULL", EINVAL);
-			return (EINVAL);
-		} else if (cmp == NULL) {
-			__throw_constraint_handler_s("qsort_s : cmp == NULL", EINVAL);
-			return (EINVAL);
-		}
-	}
-#endif
-
 loop:
 	swap_cnt = 0;
 	if (n < 7) {
@@ -134,11 +116,7 @@
 			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
 			     pl -= es)
 				swapfunc(pl, pl - es, es);
-#ifdef I_AM_QSORT_S
-		return (0);
-#else
 		return;
-#endif
 	}
 	pm = (char *)a + (n / 2) * es;
 	if (n > 7) {
@@ -187,11 +165,7 @@
 			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
 			     pl -= es)
 				swapfunc(pl, pl - es, es);
-#ifdef I_AM_QSORT_S
-		return (0);
-#else
 		return;
-#endif
 	}
 
 	pn = (char *)a + n * es;
@@ -205,13 +179,7 @@
 	if (d1 <= d2) {
 		/* Recurse on left partition, then iterate on right partition */
 		if (d1 > es) {
-#if defined(I_AM_QSORT_R)
-			qsort_r(a, d1 / es, es, thunk, cmp);
-#elif defined(I_AM_QSORT_S)
-			qsort_s(a, d1 / es, es, cmp, thunk);
-#else
-			qsort(a, d1 / es, es, cmp);
-#endif
+			local_qsort(a, d1 / es, es, cmp, thunk);
 		}
 		if (d2 > es) {
 			/* Iterate rather than recurse to save stack space */
@@ -223,13 +191,7 @@
 	} else {
 		/* Recurse on right partition, then iterate on left partition */
 		if (d2 > es) {
-#if defined(I_AM_QSORT_R)
-			qsort_r(pn - d2, d2 / es, es, thunk, cmp);
-#elif defined(I_AM_QSORT_S)
-			qsort_s(pn - d2, d2 / es, es, cmp, thunk);
-#else
-			qsort(pn - d2, d2 / es, es, cmp);
-#endif
+			local_qsort(pn - d2, d2 / es, es, cmp, thunk);
 		}
 		if (d1 > es) {
 			/* Iterate rather than recurse to save stack space */
@@ -238,8 +200,44 @@
 			goto loop;
 		}
 	}
+}
+
+#if defined(I_AM_QSORT_R)
+void
+qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
+{
+	local_qsort_r(a, n, es, cmp, thunk);
+}
+#elif defined(I_AM_QSORT_S)
+errno_t
+qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
+{
+	if (n > RSIZE_MAX) {
+		__throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
+		return (EINVAL);
+	} else if (es > RSIZE_MAX) {
+		__throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
+		    EINVAL);
+		return (EINVAL);
+	} else if (n != 0) {
+		if (a == NULL) {
+			__throw_constraint_handler_s("qsort_s : a == NULL",
+			    EINVAL);
+			return (EINVAL);
+		} else if (cmp == NULL) {
+			__throw_constraint_handler_s("qsort_s : cmp == NULL",
+			    EINVAL);
+			return (EINVAL);
+		}
+	}
 
-#ifdef I_AM_QSORT_S
+	local_qsort_s(a, n, es, cmp, thunk);
 	return (0);
-#endif
 }
+#else
+void
+qsort(void *a, size_t n, size_t es, cmp_t *cmp)
+{
+	local_qsort(a, n, es, cmp, NULL);
+}
+#endif