diff --git a/cmd/five/main.go b/cmd/five/main.go
index 08d6163..4d59d58 100644
--- a/cmd/five/main.go
+++ b/cmd/five/main.go
@@ -324,6 +324,24 @@ func buildPRGWithIncludes(prgFile, output string, includes []string) {
 
 // buildMultiPRGWithIncludes is buildMultiPRG with -I support.
 func buildMultiPRGWithIncludes(prgFiles []string, output string, includes []string) {
+	// Multi-file builds bring along sibling PRGs whose own #include
+	// references a .ch file living next to them (e.g. FiveSqlDef.ch
+	// in _FiveSql2/src/). Each file's PP only adds its OWN dir by
+	// default, so a test under _FiveSql2/test/ couldn't find a .ch
+	// kept in _FiveSql2/src/. Promote every input file's dir into
+	// the shared user-include list so siblings can resolve each
+	// other's headers.
+	seen := map[string]bool{}
+	for _, dir := range includes {
+		seen[dir] = true
+	}
+	for _, f := range prgFiles {
+		dir := filepath.Dir(f)
+		if dir != "" && !seen[dir] {
+			seen[dir] = true
+			includes = append(includes, dir)
+		}
+	}
 	userIncludeDirs = includes
 	buildMultiPRG(prgFiles, output)
 }
diff --git a/tests/std_ch/run.sh b/tests/std_ch/run.sh
index 0abf7c9..5fbbb52 100755
--- a/tests/std_ch/run.sh
+++ b/tests/std_ch/run.sh
@@ -32,6 +32,7 @@ TESTS=(
    test_block_comma
    test_compound_lhs
    test_join_hash
+   test_sql_standards
 )
 
 work="$(mktemp -d)"
@@ -41,8 +42,17 @@ pass=0
 fail=0
 for name in "${TESTS[@]}"; do
    src="$ROOT/tests/std_ch/${name}.prg"
+   # test_sql_standards lives in our suite but its `#include
+   # "FiveSqlDef.ch"` resolves only when the FiveSql2 src files
+   # are part of the same build (they sit alongside the .ch).
+   # Other tests build standalone.
+   extras=()
+   if [ "$name" = "test_sql_standards" ]; then
+      src="$ROOT/_FiveSql2/test/test_sql_standards.prg"
+      extras=( $ROOT/_FiveSql2/src/*.prg )
+   fi
    bin="$work/${name}"
-   if ! "$FIVE" build "$src" -o "$bin" >/dev/null 2>"$work/${name}.err"; then
+   if ! "$FIVE" build "$src" "${extras[@]}" -o "$bin" >/dev/null 2>"$work/${name}.err"; then
       echo "FAIL build  $name"
       cat "$work/${name}.err" | sed 's/^/   /'
       fail=$((fail+1))