diff --git a/cbmc/proofs/poly_frommsg/Makefile b/cbmc/proofs/poly_frommsg/Makefile
index 4b06d186f..d1953ab84 100644
--- a/cbmc/proofs/poly_frommsg/Makefile
+++ b/cbmc/proofs/poly_frommsg/Makefile
@@ -25,7 +25,7 @@ USE_DYNAMIC_FRAMES=1
 
 # Disable any setting of EXTERNAL_SAT_SOLVER, and choose SMT backend instead
 EXTERNAL_SAT_SOLVER=
-CBMCFLAGS=--bitwuzla
+CBMCFLAGS=--smt2
 
 FUNCTION_NAME = $(MLKEM_NAMESPACE)poly_frommsg