diff --git a/doc/c128.sgml b/doc/c128.sgml
index 84b601ab7..82c280ef0 100644
--- a/doc/c128.sgml
+++ b/doc/c128.sgml
@@ -342,7 +342,7 @@ The default drivers, <tt/mouse_stddrv (mouse_static_stddrv)/, point to <tt/c128-
 <sect1>Realtime clock<p>
 
 The realtime clock functions use the CIA1 TOD clock. As that clock only stores
-the time but not the date, the date set by <tt/clock_settime()/ ist simply stored
+the time but not the date, the date set by <tt/clock_settime()/ is simply stored
 inside the C library for retrieval in the same program via <tt/clock_gettime()/.
 
 
diff --git a/doc/c64.sgml b/doc/c64.sgml
index 8c910666c..37ac0c146 100644
--- a/doc/c64.sgml
+++ b/doc/c64.sgml
@@ -421,7 +421,7 @@ The default drivers, <tt/mouse_stddrv (mouse_static_stddrv)/, point to <tt/c64-1
 <sect1>Realtime clock<p>
 
 The realtime clock functions use the CIA1 TOD clock. As that clock only stores
-the time but not the date, the date set by <tt/clock_settime()/ ist simply stored
+the time but not the date, the date set by <tt/clock_settime()/ is simply stored
 inside the C library for retrieval in the same program via <tt/clock_gettime()/.
 
 
diff --git a/doc/cbm510.sgml b/doc/cbm510.sgml
index 5df8f06f6..600a1fe90 100644
--- a/doc/cbm510.sgml
+++ b/doc/cbm510.sgml
@@ -245,7 +245,7 @@ The default drivers, <tt/mouse_stddrv (mouse_static_stddrv)/, point to <tt/cbm51
 <sect1>Realtime clock<p>
 
 The realtime clock functions use the CIA1 TOD clock. As that clock only stores
-the time but not the date, the date set by <tt/clock_settime()/ ist simply stored
+the time but not the date, the date set by <tt/clock_settime()/ is simply stored
 inside the C library for retrieval in the same program via <tt/clock_gettime()/.
 
 
diff --git a/doc/cbm610.sgml b/doc/cbm610.sgml
index 49313c4d2..68b1060ad 100644
--- a/doc/cbm610.sgml
+++ b/doc/cbm610.sgml
@@ -227,7 +227,7 @@ No mouse drivers are currently available for the Commodore 610.
 <sect1>Realtime clock<p>
 
 The realtime clock functions use the CIA1 TOD clock. As that clock only stores
-the time but not the date, the date set by <tt/clock_settime()/ ist simply stored
+the time but not the date, the date set by <tt/clock_settime()/ is simply stored
 inside the C library for retrieval in the same program via <tt/clock_gettime()/.