diff --git a/scripts/dpdk/report-krnlmon-coverage.sh b/scripts/dpdk/report-krnlmon-coverage.sh
index ad8002df..8ee61f44 100755
--- a/scripts/dpdk/report-krnlmon-coverage.sh
+++ b/scripts/dpdk/report-krnlmon-coverage.sh
@@ -31,7 +31,7 @@ TEST_LABEL=krnlmon
 mkdir -p ${OUTPUT_DIR}
 
 # Empty it for good measure.
-rm -fr ${OUTPUT_DIR}/*
+rm -fr ${OUTPUT_DIR:?}/*
 
 # Capture the coverage data, excluding files in directories
 # that don't interest us.
diff --git a/scripts/dpdk/report-ovsp4rt-coverage.sh b/scripts/dpdk/report-ovsp4rt-coverage.sh
index 1f8084d4..295baef3 100755
--- a/scripts/dpdk/report-ovsp4rt-coverage.sh
+++ b/scripts/dpdk/report-ovsp4rt-coverage.sh
@@ -31,7 +31,7 @@ TEST_LABEL=ovsp4rt
 mkdir -p ${OUTPUT_DIR}
 
 # Empty it for good measure.
-rm -fr ${OUTPUT_DIR}/*
+rm -fr ${OUTPUT_DIR:?}/*
 
 # Capture the coverage data, excluding files in directories
 # that don't interest us.
diff --git a/scripts/es2k/report-krnlmon-coverage.sh b/scripts/es2k/report-krnlmon-coverage.sh
index 76a04ec8..af410409 100755
--- a/scripts/es2k/report-krnlmon-coverage.sh
+++ b/scripts/es2k/report-krnlmon-coverage.sh
@@ -31,7 +31,7 @@ TEST_LABEL=krnlmon
 mkdir -p ${OUTPUT_DIR}
 
 # Empty it for good measure.
-rm -fr ${OUTPUT_DIR}/*
+rm -fr ${OUTPUT_DIR:?}/*
 
 # Capture the coverage data, excluding files in directories
 # that don't interest us.
diff --git a/scripts/es2k/report-ovsp4rt-coverage.sh b/scripts/es2k/report-ovsp4rt-coverage.sh
index 336c3180..e3795704 100755
--- a/scripts/es2k/report-ovsp4rt-coverage.sh
+++ b/scripts/es2k/report-ovsp4rt-coverage.sh
@@ -31,7 +31,7 @@ TEST_LABEL=ovsp4rt
 mkdir -p ${OUTPUT_DIR}
 
 # Empty it for good measure.
-rm -fr ${OUTPUT_DIR}/*
+rm -fr ${OUTPUT_DIR:?}/*
 
 # Capture the coverage data, excluding files in directories
 # that don't interest us.