diff --git a/src/analyze.cpp b/src/analyze.cpp
index e4ccf699ba..30f4d44cac 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -253,6 +253,7 @@ bool type_has_zero_bits_known(TypeTableEntry *type_entry) {
 
 
 uint64_t type_size(CodeGen *g, TypeTableEntry *type_entry) {
+    assert(type_is_complete(type_entry));
     if (type_has_bits(type_entry)) {
         return LLVMStoreSizeOfType(g->target_data_ref, type_entry->type_ref);
     } else {
diff --git a/src/ir.cpp b/src/ir.cpp
index d71079d77f..908499779d 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -9904,6 +9904,9 @@ static TypeTableEntry *ir_analyze_instruction_size_of(IrAnalyze *ira,
     IrInstruction *type_value = size_of_instruction->type_value->other;
     TypeTableEntry *type_entry = ir_resolve_type(ira, type_value);
     TypeTableEntry *canon_type_entry = get_underlying_type(type_entry);
+
+    ensure_complete_type(ira->codegen, type_entry);
+
     switch (canon_type_entry->id) {
         case TypeTableEntryIdInvalid:
             return ira->codegen->builtin_types.entry_invalid;