diff --git a/share/man/man4/acpi.4 b/share/man/man4/acpi.4
index 0da6f602e7a9..2a213738c38f 100644
--- a/share/man/man4/acpi.4
+++ b/share/man/man4/acpi.4
@@ -317,7 +317,7 @@ Try increasing this number if you get the error
 Enables calling the VESA reset BIOS vector on the resume path.
 Some graphic chips have problems such as LCD white-out after resume.
 Try setting this to 0 if this causes problems for you.
-.It Va hw.acpi.os_name
+.It Va hw.acpi.osname
 Some systems' ASL may have problems because they look for names
 of Microsoft operating systems.
 This tunable overrides the value of the
diff --git a/sys/boot/forth/loader.conf.5 b/sys/boot/forth/loader.conf.5
index 89a803f7cf4c..414784e95568 100644
--- a/sys/boot/forth/loader.conf.5
+++ b/sys/boot/forth/loader.conf.5
@@ -132,6 +132,10 @@ special value
 .Dq abort ,
 which aborts the bootstrap process, use of this setting should be avoided.
 .El
+.Pp
+.Em WARNING:
+developers should never use these suffixes for any kernel environment
+variables (tunables) or conflicts will result.
 .Sh DEFAULT SETTINGS
 Most of
 .Nm Ns 's
diff --git a/sys/dev/acpica/Osd/OsdTable.c b/sys/dev/acpica/Osd/OsdTable.c
index 2f057d2a10a1..0b94ad3bc5db 100644
--- a/sys/dev/acpica/Osd/OsdTable.c
+++ b/sys/dev/acpica/Osd/OsdTable.c
@@ -38,8 +38,8 @@
 #undef _COMPONENT
 #define _COMPONENT      ACPI_TABLES
 
-static char acpi_os_name[128];
-TUNABLE_STR("hw.acpi.os_name", acpi_os_name, sizeof(acpi_os_name));
+static char acpi_osname[128];
+TUNABLE_STR("hw.acpi.osname", acpi_osname, sizeof(acpi_osname));
 
 ACPI_STATUS
 AcpiOsPredefinedOverride (
@@ -50,11 +50,9 @@ AcpiOsPredefinedOverride (
 	return (AE_BAD_PARAMETER);
 
     *NewVal = NULL;
-    if (strncmp(InitVal->Name, "_OS_", 4) == 0 &&
-	getenv_string("hw.acpi.os_name", acpi_os_name, sizeof(acpi_os_name))) {
-
-	printf("ACPI: Overriding _OS definition with \"%s\"\n", acpi_os_name);
-	*NewVal = acpi_os_name;
+    if (strncmp(InitVal->Name, "_OS_", 4) == 0 && strlen(acpi_osname) > 0) {
+	printf("ACPI: Overriding _OS definition with \"%s\"\n", acpi_osname);
+	*NewVal = acpi_osname;
     }
 
     return (AE_OK);
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index fe75bf21b3e5..d0f449d49919 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -265,6 +265,9 @@ void	sysinit_add(struct sysinit **set, struct sysinit **set_end);
  * Infrastructure for tunable 'constants'.  Value may be specified at compile
  * time or kernel load time.  Rules relating tunables together can be placed
  * in a SYSINIT function at SI_SUB_TUNABLES with SI_ORDER_LAST.
+ *
+ * WARNING: developers should never use the reserved suffixes specified in
+ * loader.conf(5) for any tunables or conflicts will result.
  */
 
 extern void tunable_int_init(void *);