diff --git a/tools/mockup.sh b/tools/mockup.sh
index ef66fa0de..b48686536 100755
--- a/tools/mockup.sh
+++ b/tools/mockup.sh
@@ -19,22 +19,27 @@ for SYMBOL; do
     # If there are multiple declarations, pick first (eg. common/memleak.h
     # has notleak_ as a declaration, and then an inline).
     WHERE=$(grep -nH "^[a-zA-Z0-9_ (),]* [*]*$SYMBOL(" ./*/*.h | head -n1)
-    if [ x"$WHERE" != x ]; then
-	# \n on RHS is a GNU extension, and we want to work on FreeBSD
-	# shellcheck disable=SC1004
-	STUB='\
-{ fprintf(stderr, "'$SYMBOL' called!\\n"); abort(); }'
-    else
+    if [ x"$WHERE" = x ]; then
 	echo "/* Could not find declaration for $SYMBOL */"
 	continue
     fi
 
-    echo "/* Generated stub for $SYMBOL */"
     FILE=${WHERE%%:*}
     FILE_AND_LINE=${WHERE%:*}
     LINE=${FILE_AND_LINE#*:}
     END=$(tail -n "+${LINE}" < "$FILE" | grep -n ';$');
     NUM=${END%%:*}
 
+    if grep -q "$SYMBOL.*mock empty" "$FILE"; then
+	STUB="{ }"
+    else
+	# \n on RHS is a GNU extension, and we want to work on FreeBSD
+	# shellcheck disable=SC1004
+	STUB='\
+{ fprintf(stderr, "'$SYMBOL' called!\\n"); abort(); }'
+    fi
+
+    echo "/* Generated stub for $SYMBOL */"
+
     tail -n "+${LINE}" < "$FILE" | head -n "$NUM" | sed 's/^extern *//' | sed 's/PRINTF_FMT([^)]*)//' | sed 's/NON_NULL_ARGS([^)]*)//' | sed 's/NO_NULL_ARGS//g' | sed 's/NORETURN//g' | sed 's/LAST_ARG_NULL//g' | sed 's/WARN_UNUSED_RESULT//g' | sed 's/,/ UNNEEDED,/g' | sed 's/\([a-z0-9A-Z*_]* [a-z0-9A-Z*_]*\));/\1 UNNEEDED);/' | sed "s/;\$/$STUB/" | sed 's/\s*$//'
 done