diff --git a/test/test_perf_cli.sh b/test/test_perf_cli.sh
index 1eed7dce..abcbb08b 100755
--- a/test/test_perf_cli.sh
+++ b/test/test_perf_cli.sh
@@ -19,7 +19,9 @@ s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
 # -f %e gives elapsed wall clock time but is not available on all systems
 # so we use time -p for POSIX compliance and awk to get wall clock time
 # Note sometimes time -p is used and sometimes $TIMEFN, cant get it to work same everywhere
+# time function (this is a mess to get right on freebsd/linux)
 : ${TIMEFN:=time -p} # portability: 2>&1 | awk '/real/ {print $2}'
+if ! $TIMEFN true; then err "A working time function" "'$TIMEFN' does not work"; fi
 
 APPNAME=example
 
diff --git a/test/test_perf_netconf.sh b/test/test_perf_netconf.sh
index d523e4b4..441ecc4b 100755
--- a/test/test_perf_netconf.sh
+++ b/test/test_perf_netconf.sh
@@ -20,7 +20,9 @@ s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
 # -f %e gives elapsed wall clock time but is not available on all systems
 # so we use time -p for POSIX compliance and awk to get wall clock time
 # Note sometimes time -p is used and sometimes $TIMEFN, cant get it to work same everywhere
+# time function (this is a mess to get right on freebsd/linux)
 : ${TIMEFN:=time -p} # portability: 2>&1 | awk '/real/ {print $2}'
+if ! $TIMEFN true; then err "A working time function" "'$TIMEFN' does not work"; fi
 
 APPNAME=example
 
diff --git a/test/test_perf_restconf.sh b/test/test_perf_restconf.sh
index 49dc2c3a..e6d3c58c 100755
--- a/test/test_perf_restconf.sh
+++ b/test/test_perf_restconf.sh
@@ -21,6 +21,7 @@ s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
 # so we use time -p for POSIX compliance and awk to get wall clock time
 # Note sometimes time -p is used and sometimes $TIMEFN, cant get it to work same everywhere
 : ${TIMEFN:=time -p} # portability: 2>&1 | awk '/real/ {print $2}'
+if ! $TIMEFN true; then err "A working time function" "'$TIMEFN' does not work"; fi
 
 APPNAME=example
 
diff --git a/test/test_perf_state.sh b/test/test_perf_state.sh
index 020353d6..6c93787b 100755
--- a/test/test_perf_state.sh
+++ b/test/test_perf_state.sh
@@ -20,6 +20,7 @@ fin=$dir/fin
 
 # time function (this is a mess to get right on freebsd/linux)
 : ${TIMEFN:=time -p} # portability: 2>&1 | awk '/real/ {print $2}'
+if ! $TIMEFN true; then err "A working time function" "'$TIMEFN' does not work"; fi
 
 APPNAME=example
 
diff --git a/test/test_perf_state_only.sh b/test/test_perf_state_only.sh
index 471ed06b..66ae3b18 100755
--- a/test/test_perf_state_only.sh
+++ b/test/test_perf_state_only.sh
@@ -20,6 +20,7 @@ s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
 
 # time function (this is a mess to get right on freebsd/linux)
 : ${TIMEFN:=time -p} # portability: 2>&1 | awk '/real/ {print $2}'
+if ! $TIMEFN true; then err "A working time function" "'$TIMEFN' does not work"; fi
 
 APPNAME=example