diff --git a/src/coding.c b/src/coding.c
index d5833a98c23..dd767c80ab4 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -159,6 +159,9 @@ detect_coding_XXX (struct coding_system *coding,
   const unsigned char *src = coding->source;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
+  /* Some encodings do not need this variable, however it is incremented in the
+     ONE_MORE_BYTE macro.  In that case mark it with MAYBE_UNUSED to silence
+     compiler warnings.  */
   ptrdiff_t consumed_chars = 0;
   int found = 0;
   ...;
@@ -652,11 +655,6 @@ growable_destination (struct coding_system *coding)
     consumed_chars++;					\
   } while (0)
 
-/* Suppress clang warnings about consumed_chars never being used.
-   Although correct, the warnings are too much trouble to code around.  */
-#if 13 <= __clang_major__ - defined __apple_build_version__
-# pragma clang diagnostic ignored "-Wunused-but-set-variable"
-#endif
 
 /* Safely get two bytes from the source text pointed by SRC which ends
    at SRC_END, and set C1 and C2 to those bytes while skipping the
@@ -1135,7 +1133,7 @@ detect_coding_utf_8 (struct coding_system *coding,
   const unsigned char *src = coding->source, *src_base;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   bool bom_found = 0;
   ptrdiff_t nchars = coding->head_ascii;
 
@@ -1843,7 +1841,7 @@ detect_coding_emacs_mule (struct coding_system *coding,
   const unsigned char *src = coding->source, *src_base;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   int c;
   int found = 0;
 
@@ -2933,7 +2931,7 @@ detect_coding_iso_2022 (struct coding_system *coding,
   bool single_shifting = 0;
   int id;
   int c, c1;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   int i;
   int rejected = 0;
   int found = 0;
@@ -4321,7 +4319,7 @@ encode_designation_at_bol (struct coding_system *coding,
   /* Table of charsets to be designated to each graphic register.  */
   int r[4];
   int c, found = 0, reg;
-  ptrdiff_t produced_chars = 0;
+  MAYBE_UNUSED ptrdiff_t produced_chars = 0;
   bool multibytep = coding->dst_multibyte;
   Lisp_Object attrs;
   Lisp_Object charset_list;
@@ -4583,7 +4581,7 @@ detect_coding_sjis (struct coding_system *coding,
   const unsigned char *src = coding->source, *src_base;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   int found = 0;
   int c;
   Lisp_Object attrs, charset_list;
@@ -4638,7 +4636,7 @@ detect_coding_big5 (struct coding_system *coding,
   const unsigned char *src = coding->source, *src_base;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   int found = 0;
   int c;
 
@@ -5076,7 +5074,7 @@ detect_coding_ccl (struct coding_system *coding,
   const unsigned char *src = coding->source, *src_base;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   int found = 0;
   unsigned char *valids;
   ptrdiff_t head_ascii = coding->head_ascii;
@@ -5371,7 +5369,7 @@ detect_coding_charset (struct coding_system *coding,
   const unsigned char *src = coding->source, *src_base;
   const unsigned char *src_end = coding->source + coding->src_bytes;
   bool multibytep = coding->src_multibyte;
-  ptrdiff_t consumed_chars = 0;
+  MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
   Lisp_Object attrs, valids, name;
   int found = 0;
   ptrdiff_t head_ascii = coding->head_ascii;
@@ -7100,7 +7098,7 @@ produce_chars (struct coding_system *coding, Lisp_Object translation_table,
 	  if (coding->src_multibyte)
 	    {
 	      bool multibytep = 1;
-	      ptrdiff_t consumed_chars = 0;
+	      MAYBE_UNUSED ptrdiff_t consumed_chars = 0;
 
 	      while (1)
 		{