diff --git a/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c b/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
--- a/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
@@ -6374,6 +6374,14 @@
 			uintptr_t s2 = regs[r2];
 			size_t lim1, lim2;
 
+			/*
+			 * If one of the strings is NULL then the limit becomes
+			 * 0 which compares 0 characters in dtrace_strncmp()
+			 * resulting in a false positive.  dtrace_strncmp()
+			 * treats a NULL as an empty 1-char string.
+			 */
+			lim1 = lim2 = 1;
+
 			if (s1 != 0 &&
 			    !dtrace_strcanload(s1, sz, &lim1, mstate, vstate))
 				break;
diff --git a/sys/modules/dtrace/dtrace/Makefile b/sys/modules/dtrace/dtrace/Makefile
--- a/sys/modules/dtrace/dtrace/Makefile
+++ b/sys/modules/dtrace/dtrace/Makefile
@@ -61,6 +61,5 @@
 CFLAGS.dtrace_asm.S+= -D_SYS_ERRNO_H_ -D_SYS_PARAM_H_ -DLOCORE
 CWARNFLAGS+=	${OPENZFS_CWARNFLAGS}
 CWARNFLAGS+=	-Wno-parentheses
-CWARNFLAGS+=	-Wno-uninitialized
 CWARNFLAGS+=	-Wno-cast-qual
 CWARNFLAGS+=	-Wno-unused