diff --git a/build/klh10/start b/build/klh10/start
index c53dcd62..cf9fabf5 100755
--- a/build/klh10/start
+++ b/build/klh10/start
@@ -8,7 +8,7 @@ EXIT=:
 trap "" QUIT INT TERM
 
 started() {
-    EXIT="$EXIT;stop $1 $2"
+    EXIT="$EXIT;stop \"$1\" $2"
     trap "$EXIT" EXIT
     echo "$1 started, pid $2"
 }
diff --git a/build/pdp10-ka/start b/build/pdp10-ka/start
index af1581b6..c9cd335a 100755
--- a/build/pdp10-ka/start
+++ b/build/pdp10-ka/start
@@ -10,7 +10,7 @@ EXIT=:
 trap "" QUIT INT TERM
 
 started() {
-    EXIT="$EXIT;stop $1 $2"
+    EXIT="$EXIT;stop \"$1\" $2"
     trap "$EXIT" EXIT
     echo "$1 started, pid $2"
 }
diff --git a/build/pdp10-kl/start b/build/pdp10-kl/start
index dcc44111..60954beb 100755
--- a/build/pdp10-kl/start
+++ b/build/pdp10-kl/start
@@ -8,7 +8,7 @@ EXIT=:
 trap "" QUIT INT TERM
 
 started() {
-    EXIT="$EXIT;stop $1 $2"
+    EXIT="$EXIT;stop \"$1\" $2"
     trap "$EXIT" EXIT
     echo "$1 started, pid $2"
 }
diff --git a/build/pdp10-ks/start b/build/pdp10-ks/start
index 1d14d7a4..d1e21cd0 100755
--- a/build/pdp10-ks/start
+++ b/build/pdp10-ks/start
@@ -7,7 +7,7 @@ EXIT=:
 trap "" QUIT INT TERM
 
 started() {
-    EXIT="$EXIT;stop $1 $2"
+    EXIT="$EXIT;stop \"$1\" $2"
     trap "$EXIT" EXIT
     echo "$1 started, pid $2"
 }
diff --git a/build/simh/start b/build/simh/start
index 8b994f9b..5eb65cf1 100755
--- a/build/simh/start
+++ b/build/simh/start
@@ -7,7 +7,7 @@ EXIT=:
 trap "" QUIT INT TERM
 
 started() {
-    EXIT="$EXIT;stop $1 $2"
+    EXIT="$EXIT;stop \"$1\" $2"
     trap "$EXIT" EXIT
     echo "$1 started, pid $2"
 }
diff --git a/build/simhv3/start b/build/simhv3/start
index e30cad95..310baf91 100755
--- a/build/simhv3/start
+++ b/build/simhv3/start
@@ -7,7 +7,7 @@ EXIT=:
 trap "" QUIT INT TERM
 
 started() {
-    EXIT="$EXIT;stop $1 $2"
+    EXIT="$EXIT;stop \"$1\" $2"
     trap "$EXIT" EXIT
     echo "$1 started, pid $2"
 }