diff --git a/pkgs/development/libraries/glibc/common.nix b/pkgs/development/libraries/glibc/common.nix
index 2559dea2653..da1d4f08fa2 100644
--- a/pkgs/development/libraries/glibc/common.nix
+++ b/pkgs/development/libraries/glibc/common.nix
@@ -69,8 +69,11 @@ stdenv.mkDerivation ({
     + ''
       echo "LDFLAGS-nscd += -static-libgcc" >> nscd/Makefile
     ''
-    # Replace the date and time in nscd by $out.
-    #  It is used as a protocol compatibility check.
+    # Replace the date and time in nscd by a prefix of $out.
+    # It is used as a protocol compatibility check.
+    # Note: the size of the struct changes, but using only a part
+    # would break hash-rewriting. When receiving stats it does check
+    # that the struct sizes match and can't cause overflow or something.
     + ''
       cat ${./glibc-remove-datetime-from-nscd.patch} \
         | sed "s,@out@,$out," | patch -p1
diff --git a/pkgs/development/libraries/glibc/glibc-remove-datetime-from-nscd.patch b/pkgs/development/libraries/glibc/glibc-remove-datetime-from-nscd.patch
index 0a5456ea5c4..db010e62366 100644
--- a/pkgs/development/libraries/glibc/glibc-remove-datetime-from-nscd.patch
+++ b/pkgs/development/libraries/glibc/glibc-remove-datetime-from-nscd.patch
@@ -5,7 +5,7 @@
  
  /* We use this to make sure the receiver is the same.  */
 -static const char compilation[21] = __DATE__ " " __TIME__;
-+static const char compilation[21] = "@out@";
++static const char compilation[] = "@out@";
  
  /* Statistic data for one database.  */
  struct dbstat