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diff --git a/utf.c b/utf.c
index d699ccf1..19e4be51 100644
--- a/utf.c
+++ b/utf.c
@@ -3197,18 +3197,30 @@ static C_char *utf8_decode(C_char *buf, C_u32 *c, int *e)
      * shifted out.
      */
     *c  = (C_u32)(s[0] & masks[len]) << 18;
-    *c |= (C_u32)(s[1] & 0x3f) << 12;
-    *c |= (C_u32)(s[2] & 0x3f) <<  6;
-    *c |= (C_u32)(s[3] & 0x3f) <<  0;
+    if (s[0] != '\0') {
+      *c |= (C_u32)(s[1] & 0x3f) << 12;
+      if (s[1] != '\0') {
+        *c |= (C_u32)(s[2] & 0x3f) <<  6;
+        if (s[2] != '\0') {
+          *c |= (C_u32)(s[3] & 0x3f) <<  0;
+        }
+      }
+    }
     *c >>= shiftc[len];
 
     /* Accumulate the various error conditions. */
     *e  = (*c < mins[len]) << 6; // non-canonical encoding
     *e |= ((*c >> 11) == 0x1b) << 7;  // surrogate half?
     *e |= (*c > 0x10FFFF) << 8;  // out of range?
-    *e |= (s[1] & 0xc0) >> 2;
-    *e |= (s[2] & 0xc0) >> 4;
-    *e |= (s[3]       ) >> 6;
+    if (s[0] != '\0') {
+      *e |= (s[1] & 0xc0) >> 2;
+      if (s[1] != '\0') {
+        *e |= (s[2] & 0xc0) >> 4;
+        if (s[2] != '\0') {
+          *e |= (s[3]       ) >> 6;
+        }
+      }
+    }
     *e ^= 0x2a; // top two bits of each tail byte correct?
     *e >>= shifte[len];