diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index 94d3b137699..0a1df50dbb9 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -4159,7 +4159,12 @@ void FunctionValidator::visitFunction(Function* curr) {
                curr->name,
                "all used types should be allowed");
 
-  if (!curr->imported()) {
+  if (curr->imported()) {
+    shouldBeTrue(
+      curr->type.isInexact() || getModule()->features.hasCustomDescriptors(),
+      curr->name,
+      "exact imports require custom descriptors [--enable-custom-descriptors]");
+  } else {
     shouldBeTrue(
       curr->type.isExact(), curr->name, "defined function should be exact");
   }
diff --git a/test/lit/validation/exact-import.wast b/test/lit/validation/exact-import.wast
new file mode 100644
index 00000000000..318d397cfcb
--- /dev/null
+++ b/test/lit/validation/exact-import.wast
@@ -0,0 +1,9 @@
+;; Test that exact imports require custom descriptors.
+
+;; RUN: not wasm-opt %s -all --disable-custom-descriptors 2>&1 | filecheck %s
+
+;; CHECK: exact imports require custom descriptors [--enable-custom-descriptors]
+
+(module
+  (import "" "" (func $f (exact)))
+)