diff --git a/analyze-linuxcnc-wasm-blockers.sh b/analyze-linuxcnc-wasm-blockers.sh
index a21e465..57328c0 100755
--- a/analyze-linuxcnc-wasm-blockers.sh
+++ b/analyze-linuxcnc-wasm-blockers.sh
@@ -63,11 +63,21 @@ wasm_safe_shim_in_build() {
 
 core_sources=()
 blocked_sources=()
-while IFS=: read -r group path note extra; do
-    case "$group" in
+manifest_line_number=0
+while IFS= read -r manifest_line || [[ -n "$manifest_line" ]]; do
+    manifest_line_number=$((manifest_line_number + 1))
+    case "$manifest_line" in
         ""|\#*)
             continue
             ;;
+    esac
+
+    IFS=: read -r group path note extra <<<"$manifest_line"
+    if [[ -z "$group" || -z "$path" || -z "$note" || -n "${extra:-}" ]]; then
+        echo "bad manifest line $manifest_line_number: $manifest_line" >&2
+        exit 1
+    fi
+    case "$group" in
         core)
             core_sources+=("$path")
             ;;
diff --git a/test-linuxcnc-wasm-blockers.sh b/test-linuxcnc-wasm-blockers.sh
index 4fa7877..36570f1 100755
--- a/test-linuxcnc-wasm-blockers.sh
+++ b/test-linuxcnc-wasm-blockers.sh
@@ -43,11 +43,13 @@ missing_source_manifest=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_wasm_blocker_m
 missing_source_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_wasm_blocker_manifest_source.XXXXXX.log")
 duplicate_manifest=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_duplicate_wasm_blocker_manifest.XXXXXX.txt")
 duplicate_manifest_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_duplicate_wasm_blocker_manifest.XXXXXX.log")
+bad_line_manifest=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_bad_wasm_blocker_manifest_line.XXXXXX.txt")
+bad_line_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_bad_wasm_blocker_manifest_line.XXXXXX.log")
 missing_replacement_manifest=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_wasm_blocked_replacement.XXXXXX.txt")
 missing_replacement_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_wasm_blocked_replacement.XXXXXX.log")
-trap 'rm -f "$missing_manifest" "$missing_manifest_log" "$missing_root_log" "$missing_source_manifest" "$missing_source_log" "$duplicate_manifest" "$duplicate_manifest_log" "$missing_replacement_manifest" "$missing_replacement_log"' EXIT
+trap 'rm -f "$missing_manifest" "$missing_manifest_log" "$missing_root_log" "$missing_source_manifest" "$missing_source_log" "$duplicate_manifest" "$duplicate_manifest_log" "$bad_line_manifest" "$bad_line_log" "$missing_replacement_manifest" "$missing_replacement_log"' EXIT
 if ! awk '
-    /^trap '\''rm -f "\$missing_manifest" "\$missing_manifest_log" "\$missing_root_log" "\$missing_source_manifest" "\$missing_source_log" "\$duplicate_manifest" "\$duplicate_manifest_log" "\$missing_replacement_manifest" "\$missing_replacement_log"'\'' EXIT$/ { found_trap = 1 }
+    /^trap '\''rm -f "\$missing_manifest" "\$missing_manifest_log" "\$missing_root_log" "\$missing_source_manifest" "\$missing_source_log" "\$duplicate_manifest" "\$duplicate_manifest_log" "\$bad_line_manifest" "\$bad_line_log" "\$missing_replacement_manifest" "\$missing_replacement_log"'\'' EXIT$/ { found_trap = 1 }
     END { exit !found_trap }
 ' test-linuxcnc-wasm-blockers.sh; then
     echo "wasm blocker scan cleanup trap no longer covers fixed blocker temporaries" >&2
@@ -106,6 +108,17 @@ if ! grep -F "duplicate manifest source: src/emc/rs274ngc/interp_arc.cc" "$dupli
     exit 1
 fi
 
+printf 'core:src/emc/rs274ngc/interp_arc.cc\n' >"$bad_line_manifest"
+if ./analyze-linuxcnc-wasm-blockers.sh "$bad_line_manifest" >"$bad_line_log" 2>&1; then
+    echo "wasm blocker analyzer accepted bad manifest line" >&2
+    exit 1
+fi
+if ! grep -F "bad manifest line 1: core:src/emc/rs274ngc/interp_arc.cc" "$bad_line_log" >/dev/null; then
+    echo "wasm blocker analyzer did not report bad manifest line clearly" >&2
+    sed -n '1,20p' "$bad_line_log" >&2
+    exit 1
+fi
+
 cat >"$missing_replacement_manifest" <<'EOF'
 core:src/emc/rs274ngc/interp_arc.cc:core entry
 blocked:src/emc/tooldata/tooldata_db.cc:blocked entry without wasm replacement