diff --git a/man5/proc.5 b/man5/proc.5
index ed309380b..ac58c789a 100644
--- a/man5/proc.5
+++ b/man5/proc.5
@@ -1987,7 +1987,7 @@ contains the memory protection key (see
 associated with the virtual memory area.
 This entry is present only if the kernel was built with the
 .B CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
-configuration option.
+configuration option (since Linux 4.6).
 .IP
 The "VmFlags" line (available since Linux 3.8)
 represents the kernel flags associated with the virtual memory area,
@@ -2026,13 +2026,6 @@ encoded using the following two-letter codes:
     um  - userfaultfd missing pages tracking (since Linux 4.3)
     uw  - userfaultfd wprotect pages tracking (since Linux 4.3)
 .IP
-"ProtectionKey" field contains the memory protection key (see
-.BR pkeys (7))
-associated with the virtual memory area.
-Present only if the kernel was built with the
-.B CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
-configuration option. (since Linux 4.6)
-.IP
 The
 .IR /proc/[pid]/smaps
 file is present only if the