diff --git a/src/nfa/mcclellancompile.cpp b/src/nfa/mcclellancompile.cpp
index 3f217ed3..36545e98 100644
--- a/src/nfa/mcclellancompile.cpp
+++ b/src/nfa/mcclellancompile.cpp
@@ -620,7 +620,7 @@ bytecode_ptr<NFA> mcclellanCompile16(dfa_info &info, const CompileContext &cc,
     u8 alphaShift = info.getAlphaShift();
     assert(alphaShift <= 8);
 
-    u16 count_real_states;
+    u16 count_real_states{0};
     u16 wide_limit;
     if (!allocateFSN16(info, &count_real_states, &wide_limit)) {
         DEBUG_PRINTF("failed to allocate state numbers, %zu states total\n",