diff --git a/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java b/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
index 518b8e5e2..9ebbb3aac 100644
--- a/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
@@ -65,6 +65,7 @@ import org.teavm.model.instructions.ConstructArrayInstruction;
 import org.teavm.model.instructions.ConstructInstruction;
 import org.teavm.model.instructions.ConstructMultiArrayInstruction;
 import org.teavm.model.instructions.InstructionVisitor;
+import org.teavm.model.instructions.IsInstanceInstruction;
 import org.teavm.model.instructions.StringConstantInstruction;
 import org.teavm.model.lowlevel.CallSiteDescriptor;
 import org.teavm.model.lowlevel.Characteristics;