diff --git a/src/libutf.c b/src/libutf.c
index ab2bbb6..eec8f69 100644
--- a/src/libutf.c
+++ b/src/libutf.c
@@ -33,17 +33,17 @@ swab32(rune_t c){ return
  * and 1; letters denote nybbles here, little-endian, and certain bits are
  * labeled, also little-endian. */
 
-/* utf-8 bits             |32         |24         |16         |8
+/* utf-8 bits             |32         |24         |16
  * U+001000 to U+10FFFF | 1111 0ZYY | 10YY XXXX | 10WW WWVV | 10VV UUUU *
  * U+000800 to U+00FFFF | 0000 0000 | 1110 XXXX | 10WW WWVV | 10VV UUUU *
  * U+000080 to U+0007FF | 0000 0000 | 0000 0000 | 110W WWVV | 10VV UUUU *
  * U+000000 to U+00007F | 0000 0000 | 0000 0000 | 0000 0000 | 0VVV UUUU */
 size_t
 utf8_size(rune_t c){ return
-	1 + ((c & 0x80000000) >> 31) /* 4B? */
-	  + ((c & 0x00800000) >> 23) /* 3B? */
-	  + ((c & 0x00008000) >> 15) /* 2B? */
-	  + ((c & 0x00000080) >> 7); /* 1B? */
+	  ((c & 0x80000000) >> 31) /* 4B? */
+	+ ((c & 0x00800000) >> 23) /* 3B? */
+	+ ((c & 0x00008000) >> 15) /* 2B? */
+	+ 1;
 }
 
 char *
@@ -88,27 +88,41 @@ utf8_to_utf32be(rune_t c){ return
  * U+000000 to U+00007F | 0000 0000 | 0000 0000 | 0000 0000 | 0VVV UUUU */
 rune_t
 utf32be_to_utf8(rune_t c, size_t m){
+	size_t n;
 	rune_t r;
-	{	size_t n;
-		if((n = utf8_size(c)) > m)
-			m = n; } /* This avoids calculating the size twice. */
-	switch(m){ /* "Trin's device" if this is a novel use of a switch. */
-	case 4: r =   0xF0000000                              /* UTF-8 b32-29 */
-			    | ((c & 0x1C0000) << 6)  /* UTF-32 b21-19 -> UTF-8 b27-25 */
-				| 0x00800000                              /* UTF-8 b24-23 */
-				| ((c & 0x03F000) << 4); /* UTF-32 b18-13 -> UTF-8 b24-17 */
-	if(m == 3)
-	case 3:	r =   0x00E00000  /* 0xE == 0b1110 */         /* UTF-8 b24-21 */
-				| ((c & 0x00F000) << 4); /* UTF-32 b16-13 -> UTF-8 b20-17 */
-			r |=  0x00008000                              /* UTF-8 b16-15 */
-				| ((c & 0x000FC0) << 2); /* UTF-32 b12- 7 -> UTF-8 b14- 9 */
-	if(m == 2)
-	case 2: r =   0x0000C000  /* 0xC == 0b1100 */         /* UTF-8 b16-14 */
-				| ((c & 0x007C00) << 2); /* UTF-32 b11- 7 -> UTF-8 b13- 9 */
-			r |=  0x00000080                              /* UTF-8 b 8- 7 */
-				| (c & 0x00003F);                         /* UTF-8 b 6- 1 */
-	if(m == 1)
-	case 1: r = c & 0x00007F; /* 0x7 == 0b0111 */         /* UTF-8 b 7- 1 */
+
+	if((n = utf8_size(c)) > m)
+		m = n;
+
+	/* In tested compilers this generates roughly the same assembly as the
+	 * naive (no fallthroughs) approach. */
+	switch(m){
+	case 4:
+		r =   0xF0000000                              /* UTF-8 b32-29 */
+		    | ((c & 0x1C0000) << 6)  /* UTF-32 b21-19 -> UTF-8 b27-25 */
+
+	r |=  0x00800000                                  /* UTF-8 b24-23 */
+	    | ((c & 0x03F000) << 4);     /* UTF-32 b18-13 -> UTF-8 b24-17 */
+
+	if(0)  /* if(m == 3) */
+	case 3:
+		r =   0x00E00000  /* 0xE == 0b1110 */         /* UTF-8 b24-21 */
+		    | ((c & 0x00F000) << 4); /* UTF-32 b16-13 -> UTF-8 b20-17 */
+
+	r |=  0x00008000                                  /* UTF-8 b16-15 */
+	    | ((c & 0x000FC0) << 2);     /* UTF-32 b12- 7 -> UTF-8 b14- 9 */
+
+	if(0)  /* if(m == 2) */
+	case 2:
+		r =   0x0000C000  /* 0xC == 0b1100 */         /* UTF-8 b16-14 */
+		    | ((c & 0x007C00) << 2); /* UTF-32 b11- 7 -> UTF-8 b13- 9 */
+
+	r |=  0x00000080                                  /* UTF-8 b 8- 7 */
+	    | (c & 0x00003F);                             /* UTF-8 b 6- 1 */
+
+	break; /* if(m == 1) */
+	case 1:
+		r = c & 0x00007F; /* 0x7 == 0b0111 */         /* UTF-8 b 7- 1 */
 	}
 	return r;
 }