diff --git a/src/Makefile.am b/src/Makefile.am
index 61196636e..7c843cba8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -415,7 +415,7 @@ libzcash_a_SOURCES = \
   zcash/prf.cpp \
   zcash/util.cpp
 
-libzcash_a_CPPFLAGS = -DMULTICORE -fopenmp -fPIC -DBINARY_OUTPUT -DCURVE_ALT_BN128 -DBOOST_SPIRIT_THREADSAFE -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS $(HARDENED_CPPFLAGS) $(HARDENED_CXXFLAGS) $(HARDENED_LDFLAGS) -pipe -O2 -O0 -g -Wstack-protector -fstack-protector-all -fPIE -fvisibility=hidden -DSTATIC $(BITCOIN_INCLUDES)
+libzcash_a_CPPFLAGS = -DMULTICORE -fopenmp -fPIC -DBINARY_OUTPUT -DCURVE_ALT_BN128 -DBOOST_SPIRIT_THREADSAFE -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS $(HARDENED_CPPFLAGS) $(HARDENED_CXXFLAGS) $(HARDENED_LDFLAGS) -pipe -O1 -g -Wstack-protector -fstack-protector-all -fPIE -fvisibility=hidden -DSTATIC $(BITCOIN_INCLUDES)
 
 # bitcoinconsensus library #
 if BUILD_BITCOIN_LIBS