diff --git a/cmd/Makefile.am b/cmd/Makefile.am
index 6d6de4adb42a..2bd9d039f20e 100644
--- a/cmd/Makefile.am
+++ b/cmd/Makefile.am
@@ -39,8 +39,6 @@ zhack_LDADD = \
 
 
 ztest_CFLAGS    = $(AM_CFLAGS) $(KERNEL_CFLAGS)
-# Get rid of compiler warning for unchecked truncating snprintfs on gcc 7.1.1
-ztest_CFLAGS   += $(NO_FORMAT_TRUNCATION)
 ztest_CPPFLAGS  = $(AM_CPPFLAGS) $(FORCEDEBUG_CPPFLAGS)
 
 sbin_PROGRAMS   += ztest
diff --git a/config/Rules.am b/config/Rules.am
index 2e463ae6083a..30c5f353cd23 100644
--- a/config/Rules.am
+++ b/config/Rules.am
@@ -21,7 +21,9 @@ AM_CFLAGS += $(IMPLICIT_FALLTHROUGH)
 AM_CFLAGS += $(DEBUG_CFLAGS)
 AM_CFLAGS += $(ASAN_CFLAGS)
 AM_CFLAGS += $(UBSAN_CFLAGS)
-AM_CFLAGS += $(CODE_COVERAGE_CFLAGS) $(NO_FORMAT_ZERO_LENGTH)
+AM_CFLAGS += $(CODE_COVERAGE_CFLAGS)
+AM_CFLAGS += $(NO_FORMAT_ZERO_LENGTH)
+AM_CFLAGS += $(NO_FORMAT_TRUNCATION)
 if BUILD_FREEBSD
 AM_CFLAGS += -fPIC -Werror -Wno-unknown-pragmas -Wno-enum-conversion
 AM_CFLAGS += -include $(top_srcdir)/include/os/freebsd/spl/sys/ccompile.h
diff --git a/include/sys/ddt_impl.h b/include/sys/ddt_impl.h
index d6693658885b..52b927b7519d 100644
--- a/include/sys/ddt_impl.h
+++ b/include/sys/ddt_impl.h
@@ -66,7 +66,12 @@ extern void ddt_stat_update(ddt_t *ddt, ddt_entry_t *dde, uint64_t neg);
  * outside of the DDT implementation proper, and if you do, consider moving
  * them up.
  */
-#define	DDT_NAMELEN	110
+
+/*
+ * Enough room to expand DMU_POOL_DDT format for all possible DDT
+ * checksum/class/type combinations.
+ */
+#define	DDT_NAMELEN	32
 
 extern uint64_t ddt_phys_total_refcnt(const ddt_entry_t *dde);