diff --git a/src/lib/config.h.in b/src/lib/config.h.in
index 357a36e28..bd078d67d 100644
--- a/src/lib/config.h.in
+++ b/src/lib/config.h.in
@@ -110,9 +110,6 @@
 /* Define to 1 if you can safely include both <sys/time.h> and <time.h>. */
 #cmakedefine TIME_WITH_SYS_TIME @TIME_WITH_SYS_TIME@
 
-/* Define to 1 if your <sys/time.h> declares `struct tm`. */
-#cmakedefine TM_IN_SYS_TIME @TM_IN_SYS_TIME@
-
 /* Define to 1 if the X Window System is missing or not being used. */
 #cmakedefine X_DISPLAY_MISSING @X_DISPLAY_MISSING@