diff --git a/lang/el-compiler/src/codegen.el b/lang/el-compiler/src/codegen.el
index 380e32a..288e1c2 100644
--- a/lang/el-compiler/src/codegen.el
+++ b/lang/el-compiler/src/codegen.el
@@ -2797,6 +2797,12 @@ fn params_to_env_args(params: [Any]) -> String {
 fn cg_fn(stmt: Map<String, Any>) -> Void {
     let fn_name: String = stmt["name"]
     state_set("__cg_current_fn", fn_name)
+    // Record every top-level definition. El has NO namespacing -- imports are
+    // textual inlining, so two modules defining the same name emit two C
+    // functions into one translation unit. cc catches it, but names the
+    // generated helpers first and the user's fn fourth. Recording it lets the
+    // collision be reported at El level, in El terms.
+    record_call(fn_name, "defines")
     // Emit which constructs this fn carries, so the prohibition check can be a
     // query over relations instead of a walk inside the emitter.
     let cdl = stmt["decorators"]
diff --git a/lang/tests/integration/definitions_query.sh b/lang/tests/integration/definitions_query.sh
new file mode 100755
index 0000000..2f31c3c
--- /dev/null
+++ b/lang/tests/integration/definitions_query.sh
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+# Control for duplicate-definition detection.
+#
+# El has no namespacing: import is textual inlining, so two modules defining the
+# same name emit two C functions into one translation unit.
+set -uo pipefail
+ELC="${1:?usage: definitions_query.sh <elc>}"
+LANG_DIR="${2:-$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)}"
+W=$(mktemp -d); trap 'rm -rf "$W"' EXIT; F=0
+chk(){ [ "$2" = "$3" ] && printf '  ok    %s\n' "$1" || { printf '  FAIL  %s\n    expected %s got %s\n' "$1" "$2" "$3"; F=$((F+1)); }; }
+
+printf 'fn helper() -> Int { return 1 }\n' > "$W/a.el"
+printf 'fn helper() -> Int { return 2 }\n' > "$W/b.el"
+printf 'import "a.el"\nimport "b.el"\nfn main() { println(int_to_str(helper())) }\n' > "$W/m.el"
+EL_RELATIONS_OUT="$W/r.txt" "$ELC" "$W/m.el" >/dev/null 2>&1
+out=$("$LANG_DIR/tools/check/definitions.sh" "$W/r.txt" 2>&1); rc=$?
+chk "a collision across modules is caught at El level" "1" "$rc"
+chk "the colliding name is reported" "1" "$(echo "$out" | grep -c "'helper' is defined 2 times")"
+chk "and the reason is given" "1" "$(echo "$out" | grep -c 'no namespacing')"
+
+printf 'fn only_once() -> Int { return 1 }\nfn main() { println(int_to_str(only_once())) }\n' > "$W/c.el"
+EL_RELATIONS_OUT="$W/r2.txt" "$ELC" "$W/c.el" >/dev/null 2>&1
+"$LANG_DIR/tools/check/definitions.sh" "$W/r2.txt" >/dev/null 2>&1
+chk "a clean program exits 0" "0" "$?"
+echo; echo "  4 assertions, $((4-F)) passed, $F failed"; exit $F
diff --git a/lang/tools/check/definitions.sh b/lang/tools/check/definitions.sh
new file mode 100755
index 0000000..b97c7f2
--- /dev/null
+++ b/lang/tools/check/definitions.sh
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# definitions.sh — catch duplicate top-level definitions at El level.
+#
+# El has no namespacing. `import` is textual inlining, so two modules defining
+# the same name emit two C functions into one translation unit. cc does catch
+# it, but reports the generated helpers (__el_body_f, __env_f, __thunk_f) before
+# the user's own function, so the first three errors name symbols the user never
+# wrote.
+#
+# LIMIT, stated rather than hidden: textual inlining destroys file provenance.
+# By the time codegen runs there is one source string and no record of which
+# file a definition came from, so this can say WHICH name collides but not which
+# files. Naming the files needs provenance threaded through resolve_imports.
+set -uo pipefail
+REL="${1:?usage: definitions.sh <relations-file>}"
+[ -f "$REL" ] || exit 0
+V=0
+while read -r name count; do
+    [ "$count" -gt 1 ] || continue
+    printf "duplicate definition: '%s' is defined %s times — El has no namespacing, so imported modules share one global scope\n" "$name" "$count"
+    V=$((V+1))
+done < <(grep ' calls defines$' "$REL" | awk '{print $1}' | sort | uniq -c | awk '{print $2, $1}')
+[ "$V" -eq 0 ] && echo "definitions: clean"
+exit "$V"