diff --git a/src/runtime/os3_solaris.go b/src/runtime/os3_solaris.go
index 349f4abbcf..9368e0d5c6 100644
--- a/src/runtime/os3_solaris.go
+++ b/src/runtime/os3_solaris.go
@@ -165,6 +165,9 @@ func newosproc(mp *m, _ unsafe.Pointer) {
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 	if ret != 0 {
 		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", ret, ")\n")
+		if ret == -_EAGAIN {
+			println("runtime: may need to increase max user processes (ulimit -u)")
+		}
 		throw("newosproc")
 	}
 }
diff --git a/src/runtime/os_dragonfly.go b/src/runtime/os_dragonfly.go
index 78a150eee5..85d4aadbfe 100644
--- a/src/runtime/os_dragonfly.go
+++ b/src/runtime/os_dragonfly.go
@@ -134,6 +134,7 @@ func newosproc(mp *m, stk unsafe.Pointer) {
 		tid2:       nil,
 	}
 
+	// TODO: Check for error.
 	lwp_create(&params)
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 }
diff --git a/src/runtime/os_freebsd.go b/src/runtime/os_freebsd.go
index 3a73b66277..c187ee805f 100644
--- a/src/runtime/os_freebsd.go
+++ b/src/runtime/os_freebsd.go
@@ -121,6 +121,7 @@ func newosproc(mp *m, stk unsafe.Pointer) {
 
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
+	// TODO: Check for error.
 	thr_new(&param, int32(unsafe.Sizeof(param)))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 }
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index 35b57d8a23..542f214a42 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -154,6 +154,9 @@ func newosproc(mp *m, stk unsafe.Pointer) {
 
 	if ret < 0 {
 		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", -ret, ")\n")
+		if ret == -_EAGAIN {
+			println("runtime: may need to increase max user processes (ulimit -u)")
+		}
 		throw("newosproc")
 	}
 }
diff --git a/src/runtime/os_netbsd.go b/src/runtime/os_netbsd.go
index 41f34f7132..4c44b2bb20 100644
--- a/src/runtime/os_netbsd.go
+++ b/src/runtime/os_netbsd.go
@@ -20,6 +20,8 @@ const (
 	// From NetBSD's <sys/ucontext.h>
 	_UC_SIGMASK = 0x01
 	_UC_CPU     = 0x04
+
+	_EAGAIN = 35
 )
 
 type mOS struct {
@@ -162,6 +164,9 @@ func newosproc(mp *m, stk unsafe.Pointer) {
 	ret := lwp_create(unsafe.Pointer(&uc), 0, unsafe.Pointer(&mp.procid))
 	if ret < 0 {
 		print("runtime: failed to create new OS thread (have ", mcount()-1, " already; errno=", -ret, ")\n")
+		if ret == -_EAGAIN {
+			println("runtime: may need to increase max user processes (ulimit -p)")
+		}
 		throw("runtime.newosproc")
 	}
 }
diff --git a/src/runtime/os_openbsd.go b/src/runtime/os_openbsd.go
index ded6b1d4ea..9a5c53ef9e 100644
--- a/src/runtime/os_openbsd.go
+++ b/src/runtime/os_openbsd.go
@@ -154,6 +154,9 @@ func newosproc(mp *m, stk unsafe.Pointer) {
 
 	if ret < 0 {
 		print("runtime: failed to create new OS thread (have ", mcount()-1, " already; errno=", -ret, ")\n")
+		if ret == -_EAGAIN {
+			println("runtime: may need to increase max user processes (ulimit -p)")
+		}
 		throw("runtime.newosproc")
 	}
 }