diff --git a/configure.ac b/configure.ac
index bca422af..c3f53f70 100644
--- a/configure.ac
+++ b/configure.ac
@@ -866,6 +866,26 @@ if test "x${je_cv_format_arg}" = "xyes" ; then
   AC_DEFINE([JEMALLOC_HAVE_ATTR_FORMAT_ARG], [ ])
 fi
 
+dnl Check for fallthrough attribute support.
+JE_CFLAGS_SAVE()
+JE_CFLAGS_ADD([-Wimplicit-fallthrough])
+JE_COMPILABLE([fallthrough attribute],
+              [#if !__has_attribute(fallthrough)
+               #error "foo"
+               #endif],
+              [int x = 0;
+               switch (x) {
+               case 0: __attribute__((__fallthrough__));
+               case 1: return 1;
+               }],
+              [je_cv_fallthrough])
+JE_CFLAGS_RESTORE()
+if test "x${je_cv_fallthrough}" = "xyes" ; then
+  AC_DEFINE([JEMALLOC_HAVE_ATTR_FALLTHROUGH], [ ])
+  JE_CFLAGS_ADD([-Wimplicit-fallthrough])
+  JE_CXXFLAGS_ADD([-Wimplicit-fallthrough])
+fi
+
 dnl Support optional additions to rpath.
 AC_ARG_WITH([rpath],
   [AS_HELP_STRING([--with-rpath=<rpath>], [Colon-separated rpath (ELF systems only)])],
diff --git a/include/jemalloc/internal/hash.h b/include/jemalloc/internal/hash.h
index 0270034e..9132b60c 100644
--- a/include/jemalloc/internal/hash.h
+++ b/include/jemalloc/internal/hash.h
@@ -104,8 +104,8 @@ hash_x86_32(const void *key, int len, uint32_t seed) {
 		uint32_t k1 = 0;
 
 		switch (len & 3) {
-		case 3: k1 ^= tail[2] << 16; JEMALLOC_FALLTHROUGH
-		case 2: k1 ^= tail[1] << 8; JEMALLOC_FALLTHROUGH
+		case 3: k1 ^= tail[2] << 16; JEMALLOC_FALLTHROUGH;
+		case 2: k1 ^= tail[1] << 8; JEMALLOC_FALLTHROUGH;
 		case 1: k1 ^= tail[0]; k1 *= c1; k1 = hash_rotl_32(k1, 15);
 			k1 *= c2; h1 ^= k1;
 		}
@@ -177,29 +177,29 @@ hash_x86_128(const void *key, const int len, uint32_t seed,
 		uint32_t k4 = 0;
 
 		switch (len & 15) {
-		case 15: k4 ^= tail[14] << 16; JEMALLOC_FALLTHROUGH
-		case 14: k4 ^= tail[13] << 8; JEMALLOC_FALLTHROUGH
+		case 15: k4 ^= tail[14] << 16; JEMALLOC_FALLTHROUGH;
+		case 14: k4 ^= tail[13] << 8; JEMALLOC_FALLTHROUGH;
 		case 13: k4 ^= tail[12] << 0;
 			k4 *= c4; k4 = hash_rotl_32(k4, 18); k4 *= c1; h4 ^= k4;
-      JEMALLOC_FALLTHROUGH
-		case 12: k3 ^= tail[11] << 24; JEMALLOC_FALLTHROUGH
-		case 11: k3 ^= tail[10] << 16; JEMALLOC_FALLTHROUGH
-		case 10: k3 ^= tail[ 9] << 8; JEMALLOC_FALLTHROUGH
+			JEMALLOC_FALLTHROUGH;
+		case 12: k3 ^= tail[11] << 24; JEMALLOC_FALLTHROUGH;
+		case 11: k3 ^= tail[10] << 16; JEMALLOC_FALLTHROUGH;
+		case 10: k3 ^= tail[ 9] << 8; JEMALLOC_FALLTHROUGH;
 		case  9: k3 ^= tail[ 8] << 0;
-		     k3 *= c3; k3 = hash_rotl_32(k3, 17); k3 *= c4; h3 ^= k3;
-         JEMALLOC_FALLTHROUGH
-		case  8: k2 ^= tail[ 7] << 24; JEMALLOC_FALLTHROUGH
-		case  7: k2 ^= tail[ 6] << 16; JEMALLOC_FALLTHROUGH
-		case  6: k2 ^= tail[ 5] << 8; JEMALLOC_FALLTHROUGH
+			k3 *= c3; k3 = hash_rotl_32(k3, 17); k3 *= c4; h3 ^= k3;
+			JEMALLOC_FALLTHROUGH;
+		case  8: k2 ^= tail[ 7] << 24; JEMALLOC_FALLTHROUGH;
+		case  7: k2 ^= tail[ 6] << 16; JEMALLOC_FALLTHROUGH;
+		case  6: k2 ^= tail[ 5] << 8; JEMALLOC_FALLTHROUGH;
 		case  5: k2 ^= tail[ 4] << 0;
 			k2 *= c2; k2 = hash_rotl_32(k2, 16); k2 *= c3; h2 ^= k2;
-      JEMALLOC_FALLTHROUGH
-		case  4: k1 ^= tail[ 3] << 24; JEMALLOC_FALLTHROUGH
-		case  3: k1 ^= tail[ 2] << 16; JEMALLOC_FALLTHROUGH
-		case  2: k1 ^= tail[ 1] << 8; JEMALLOC_FALLTHROUGH
+			JEMALLOC_FALLTHROUGH;
+		case  4: k1 ^= tail[ 3] << 24; JEMALLOC_FALLTHROUGH;
+		case  3: k1 ^= tail[ 2] << 16; JEMALLOC_FALLTHROUGH;
+		case  2: k1 ^= tail[ 1] << 8; JEMALLOC_FALLTHROUGH;
 		case  1: k1 ^= tail[ 0] << 0;
 			k1 *= c1; k1 = hash_rotl_32(k1, 15); k1 *= c2; h1 ^= k1;
-      JEMALLOC_FALLTHROUGH
+			break;
 		}
 	}
 
@@ -261,24 +261,25 @@ hash_x64_128(const void *key, const int len, const uint32_t seed,
 		uint64_t k2 = 0;
 
 		switch (len & 15) {
-		case 15: k2 ^= ((uint64_t)(tail[14])) << 48; JEMALLOC_FALLTHROUGH
-		case 14: k2 ^= ((uint64_t)(tail[13])) << 40; JEMALLOC_FALLTHROUGH
-		case 13: k2 ^= ((uint64_t)(tail[12])) << 32; JEMALLOC_FALLTHROUGH
-		case 12: k2 ^= ((uint64_t)(tail[11])) << 24; JEMALLOC_FALLTHROUGH
-		case 11: k2 ^= ((uint64_t)(tail[10])) << 16; JEMALLOC_FALLTHROUGH
-		case 10: k2 ^= ((uint64_t)(tail[ 9])) << 8;  JEMALLOC_FALLTHROUGH
+		case 15: k2 ^= ((uint64_t)(tail[14])) << 48; JEMALLOC_FALLTHROUGH;
+		case 14: k2 ^= ((uint64_t)(tail[13])) << 40; JEMALLOC_FALLTHROUGH;
+		case 13: k2 ^= ((uint64_t)(tail[12])) << 32; JEMALLOC_FALLTHROUGH;
+		case 12: k2 ^= ((uint64_t)(tail[11])) << 24; JEMALLOC_FALLTHROUGH;
+		case 11: k2 ^= ((uint64_t)(tail[10])) << 16; JEMALLOC_FALLTHROUGH;
+		case 10: k2 ^= ((uint64_t)(tail[ 9])) << 8;  JEMALLOC_FALLTHROUGH;
 		case  9: k2 ^= ((uint64_t)(tail[ 8])) << 0;
 			k2 *= c2; k2 = hash_rotl_64(k2, 33); k2 *= c1; h2 ^= k2;
-			JEMALLOC_FALLTHROUGH
-		case  8: k1 ^= ((uint64_t)(tail[ 7])) << 56; JEMALLOC_FALLTHROUGH
-		case  7: k1 ^= ((uint64_t)(tail[ 6])) << 48; JEMALLOC_FALLTHROUGH
-		case  6: k1 ^= ((uint64_t)(tail[ 5])) << 40; JEMALLOC_FALLTHROUGH
-		case  5: k1 ^= ((uint64_t)(tail[ 4])) << 32; JEMALLOC_FALLTHROUGH
-		case  4: k1 ^= ((uint64_t)(tail[ 3])) << 24; JEMALLOC_FALLTHROUGH
-		case  3: k1 ^= ((uint64_t)(tail[ 2])) << 16; JEMALLOC_FALLTHROUGH
-		case  2: k1 ^= ((uint64_t)(tail[ 1])) << 8;  JEMALLOC_FALLTHROUGH
+			JEMALLOC_FALLTHROUGH;
+		case  8: k1 ^= ((uint64_t)(tail[ 7])) << 56; JEMALLOC_FALLTHROUGH;
+		case  7: k1 ^= ((uint64_t)(tail[ 6])) << 48; JEMALLOC_FALLTHROUGH;
+		case  6: k1 ^= ((uint64_t)(tail[ 5])) << 40; JEMALLOC_FALLTHROUGH;
+		case  5: k1 ^= ((uint64_t)(tail[ 4])) << 32; JEMALLOC_FALLTHROUGH;
+		case  4: k1 ^= ((uint64_t)(tail[ 3])) << 24; JEMALLOC_FALLTHROUGH;
+		case  3: k1 ^= ((uint64_t)(tail[ 2])) << 16; JEMALLOC_FALLTHROUGH;
+		case  2: k1 ^= ((uint64_t)(tail[ 1])) << 8;  JEMALLOC_FALLTHROUGH;
 		case  1: k1 ^= ((uint64_t)(tail[ 0])) << 0;
 			k1 *= c1; k1 = hash_rotl_64(k1, 31); k1 *= c2; h1 ^= k1;
+			break;
 		}
 	}
 
diff --git a/include/jemalloc/internal/jemalloc_internal_macros.h b/include/jemalloc/internal/jemalloc_internal_macros.h
index d8ea06f6..ece3b872 100644
--- a/include/jemalloc/internal/jemalloc_internal_macros.h
+++ b/include/jemalloc/internal/jemalloc_internal_macros.h
@@ -40,13 +40,6 @@
 #define JEMALLOC_VA_ARGS_HEAD(head, ...) head
 #define JEMALLOC_VA_ARGS_TAIL(head, ...) __VA_ARGS__
 
-#if (defined(__GNUC__) || defined(__GNUG__)) && !defined(__clang__) \
-  && defined(JEMALLOC_HAVE_ATTR) && (__GNUC__ >= 7)
-#define JEMALLOC_FALLTHROUGH JEMALLOC_ATTR(fallthrough);
-#else
-#define JEMALLOC_FALLTHROUGH /* falls through */
-#endif
-
 /* Diagnostic suppression macros */
 #if defined(_MSC_VER) && !defined(__clang__)
 #  define JEMALLOC_DIAGNOSTIC_PUSH __pragma(warning(push))
diff --git a/include/jemalloc/jemalloc_defs.h.in b/include/jemalloc/jemalloc_defs.h.in
index 11c39181..032fba4d 100644
--- a/include/jemalloc/jemalloc_defs.h.in
+++ b/include/jemalloc/jemalloc_defs.h.in
@@ -13,6 +13,9 @@
 /* Defined if format(printf, ...) attribute is supported. */
 #undef JEMALLOC_HAVE_ATTR_FORMAT_PRINTF
 
+/* Defined if fallthrough attribute is supported. */
+#undef JEMALLOC_HAVE_ATTR_FALLTHROUGH
+
 /*
  * Define overrides for non-standard allocator-related functions if they are
  * present on the system.
diff --git a/include/jemalloc/jemalloc_macros.h.in b/include/jemalloc/jemalloc_macros.h.in
index 59e29558..b4469d8e 100644
--- a/include/jemalloc/jemalloc_macros.h.in
+++ b/include/jemalloc/jemalloc_macros.h.in
@@ -71,6 +71,7 @@
 #  endif
 #  define JEMALLOC_FORMAT_ARG(i)
 #  define JEMALLOC_FORMAT_PRINTF(s, i)
+#  define JEMALLOC_FALLTHROUGH
 #  define JEMALLOC_NOINLINE __declspec(noinline)
 #  ifdef __cplusplus
 #    define JEMALLOC_NOTHROW __declspec(nothrow)
@@ -109,6 +110,11 @@
 #  else
 #    define JEMALLOC_FORMAT_PRINTF(s, i)
 #  endif
+#  ifdef JEMALLOC_HAVE_ATTR_FALLTHROUGH
+#    define JEMALLOC_FALLTHROUGH JEMALLOC_ATTR(fallthrough)
+#  else
+#    define JEMALLOC_FALLTHROUGH
+#  endif
 #  define JEMALLOC_NOINLINE JEMALLOC_ATTR(noinline)
 #  define JEMALLOC_NOTHROW JEMALLOC_ATTR(nothrow)
 #  define JEMALLOC_SECTION(s) JEMALLOC_ATTR(section(s))
@@ -121,6 +127,7 @@
 #  define JEMALLOC_ALLOC_SIZE2(s1, s2)
 #  define JEMALLOC_EXPORT
 #  define JEMALLOC_FORMAT_PRINTF(s, i)
+#  define JEMALLOC_FALLTHROUGH
 #  define JEMALLOC_NOINLINE
 #  define JEMALLOC_NOTHROW
 #  define JEMALLOC_SECTION(s)
diff --git a/src/arena.c b/src/arena.c
index a60a6843..e4dd4770 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -874,7 +874,7 @@ arena_decay_stashed(tsdn_t *tsdn, arena_t *arena,
 				    arena, is_background_thread);
 				break;
 			}
-			/* Fall through. */
+			JEMALLOC_FALLTHROUGH;
 		case extent_state_muzzy:
 			extent_dalloc_wrapper(tsdn, arena, r_extent_hooks,
 			    extent);
diff --git a/src/malloc_io.c b/src/malloc_io.c
index 2fae7570..fc7ff726 100644
--- a/src/malloc_io.c
+++ b/src/malloc_io.c
@@ -135,10 +135,10 @@ malloc_strtoumax(const char *restrict nptr, char **restrict endptr, int base) {
 			break;
 		case '-':
 			neg = true;
-			/* Fall through. */
+			JEMALLOC_FALLTHROUGH;
 		case '+':
 			p++;
-			/* Fall through. */
+			JEMALLOC_FALLTHROUGH;
 		default:
 			goto label_prefix;
 		}
@@ -289,7 +289,7 @@ d2s(intmax_t x, char sign, char *s, size_t *slen_p) {
 		if (!neg) {
 			break;
 		}
-		/* Fall through. */
+		JEMALLOC_FALLTHROUGH;
 	case ' ':
 	case '+':
 		s--;
diff --git a/src/tsd.c b/src/tsd.c
index bb40af14..6c90adec 100644
--- a/src/tsd.c
+++ b/src/tsd.c
@@ -389,7 +389,7 @@ tsd_cleanup(void *arg) {
 		 * is still called for testing and completeness.
 		 */
 		assert_tsd_data_cleanup_done(tsd);
-		/* Fall through. */
+		JEMALLOC_FALLTHROUGH;
 	case tsd_state_nominal:
 	case tsd_state_nominal_slow:
 		tsd_do_data_cleanup(tsd);