diff --git a/interp/scan.go b/interp/scan.go
index a96bcb58..add2ca3b 100644
--- a/interp/scan.go
+++ b/interp/scan.go
@@ -57,6 +57,9 @@ func (e *Eval) hasSideEffects(fn llvm.Value) *sideEffectResult {
 	case "llvm.dbg.value":
 		return &sideEffectResult{severity: sideEffectNone}
 	}
+	if fn.IsDeclaration() {
+		return &sideEffectResult{severity: sideEffectLimited}
+	}
 	if e.sideEffectFuncs == nil {
 		e.sideEffectFuncs = make(map[llvm.Value]*sideEffectResult)
 	}
diff --git a/interp/scan_test.go b/interp/scan_test.go
index 226373ce..229b12ec 100644
--- a/interp/scan_test.go
+++ b/interp/scan_test.go
@@ -21,6 +21,7 @@ var scanTestTable = []struct {
 	{"readCleanGlobal", sideEffectNone, []string{"cleanGlobalInt"}},
 	{"readDirtyGlobal", sideEffectLimited, []string{"dirtyGlobalInt"}},
 	{"callFunctionPointer", sideEffectAll, []string{"functionPointer"}},
+	{"getDirtyPointer", sideEffectLimited, nil},
 }
 
 func TestScan(t *testing.T) {
diff --git a/interp/testdata/scan.ll b/interp/testdata/scan.ll
index 33ae3001..35246419 100644
--- a/interp/testdata/scan.ll
+++ b/interp/testdata/scan.ll
@@ -45,6 +45,8 @@ define i64 @readDirtyGlobal() {
   ret i64 %global
 }
 
+declare i64* @getDirtyPointer()
+
 @functionPointer = global i64()* null
 define i64 @callFunctionPointer() {
   %fp = load i64()*, i64()** @functionPointer