diff --git a/flag.go b/flag.go
index e8cecc9..57fdb95 100644
--- a/flag.go
+++ b/flag.go
@@ -704,6 +704,13 @@ func wrapN(i, slop int, s string) (string, string) {
 
 	w := strings.LastIndexAny(s[:i], " \t\n")
 	if w <= 0 {
+		// There is nowhere to break within the first `i` runes, so the
+		// leading word is wider than the line. Let that one word overflow
+		// and break after it, rather than returning all of `s` and leaving
+		// everything that follows unwrapped.
+		if x := strings.IndexAny(s[i:], " \t\n"); x >= 0 {
+			return s[:i+x], s[i+x+1:]
+		}
 		return s, ""
 	}
 	nlPos := strings.LastIndex(s[:i], "\n")
diff --git a/printusage_test.go b/printusage_test.go
index 076d13d..d4de3b8 100644
--- a/printusage_test.go
+++ b/printusage_test.go
@@ -3,6 +3,7 @@ package pflag
 import (
 	"bytes"
 	"io"
+	"strings"
 	"testing"
 )
 
@@ -72,3 +73,60 @@ func TestPrintUsage_2(t *testing.T) {
 		t.Errorf("Expected \n%s \nActual \n%s", expectedOutput2, res)
 	}
 }
+
+const expectedOutput3 = `      --mount string   a mount specification e.g.
+                       'type=bind,source=/opt,destination=/hostopt'.
+                       The rest of this description is
+                       wrapped.
+`
+
+// A word wider than the description column has to overflow, but only that
+// word: wrapping resumes on the next one.
+func TestPrintUsage_WrapsAfterUnbreakableWord(t *testing.T) {
+	f := NewFlagSet("test", ExitOnError)
+	f.String("mount", "", "a mount specification e.g. 'type=bind,source=/opt,destination=/hostopt'. The rest of this description is wrapped.")
+
+	res := f.FlagUsagesWrapped(60)
+	if res != expectedOutput3 {
+		t.Errorf("Expected \n%s \nActual \n%s", expectedOutput3, res)
+	}
+}
+
+// No line may be longer than the requested width unless it is a single word
+// that cannot be broken at all.
+func TestPrintUsage_OnlyUnbreakableWordsOverflow(t *testing.T) {
+	usages := []string{
+		"a mount specification e.g. 'type=bind,source=/opt,destination=/hostopt'. The rest of this description is wrapped.",
+		"https://example.com/a/very/long/url/that/will/not/fit/in/the/column and some words after it to wrap",
+		"averyveryverylongwordrightatthestart followed by several shorter words",
+		"short words then averyveryverylongwordinthemiddle and more words after that one",
+		"trailing text ending in anextremelylongunbreakabletokenattheveryend",
+	}
+
+	for _, width := range []int{40, 60, 80} {
+		for _, usage := range usages {
+			f := NewFlagSet("test", ExitOnError)
+			f.String("mount", "", usage)
+
+			lines := strings.Split(strings.TrimRight(f.FlagUsagesWrapped(width), "\n"), "\n")
+			if len(lines) < 2 {
+				t.Errorf("width %d, usage %q: expected the description to wrap", width, usage)
+				continue
+			}
+
+			// Continuation lines are padded to the description column, so
+			// their indent says where the description starts on every line.
+			indent := len(lines[1]) - len(strings.TrimLeft(lines[1], " "))
+
+			for _, line := range lines {
+				if len(line) <= width || indent >= len(line) {
+					continue
+				}
+				if strings.Contains(strings.TrimSpace(line[indent:]), " ") {
+					t.Errorf("width %d, usage %q: line is %d wide and still has a break point:\n%s",
+						width, usage, len(line), line)
+				}
+			}
+		}
+	}
+}