diff --git a/projects/clamav/Dockerfile b/projects/clamav/Dockerfile
index f91236d34..0b97bc37c 100644
--- a/projects/clamav/Dockerfile
+++ b/projects/clamav/Dockerfile
@@ -16,7 +16,10 @@
 
 FROM gcr.io/oss-fuzz-base/base-builder
 MAINTAINER clamav.fuzz@gmail.com
-RUN apt-get update && apt-get install -y libssl-dev libcurl4-openssl-dev
+RUN apt-get update && apt-get install -y \
+    flex bison \
+    libssl-dev \
+    libcurl4-openssl-dev
 RUN git clone --depth 1 https://github.com/Cisco-Talos/clamav-devel.git
 RUN git clone --depth 1 https://github.com/Cisco-Talos/clamav-fuzz-corpus.git
 
diff --git a/projects/clamav/build.sh b/projects/clamav/build.sh
index 716bc8a68..4b5463290 100755
--- a/projects/clamav/build.sh
+++ b/projects/clamav/build.sh
@@ -15,13 +15,30 @@
 #
 ################################################################################
 
+set -ex
+
 #
 # Build the library.
 #
 rm -rf ${WORK}/build
 mkdir -p ${WORK}/build
 cd ${WORK}/build
-ac_cv_c_mmap_anonymous=no ${SRC}/clamav-devel/configure --disable-mempool --enable-fuzz=yes --with-libjson=no --with-pcre=no --enable-static=yes --enable-shared=no --disable-llvm --host=x86_64-unknown-linux-gnu
+
+#
+# Run ./configure
+#
+ac_cv_c_mmap_anonymous=no \
+    ${SRC}/clamav-devel/configure \
+        --disable-mempool \
+        --enable-fuzz=yes \
+        --with-libjson=no \
+        --with-pcre=no \
+        --enable-static=yes \
+        --enable-shared=no \
+        --disable-llvm \
+        --host=x86_64-unknown-linux-gnu
+
+# Build libclamav
 make clean
 make -j"$(nproc)"
 
@@ -40,16 +57,16 @@ cp ./fuzz/clamav_* ${OUT}/.
 mkdir ${WORK}/all-scantype-seeds
 
 for type in ARCHIVE MAIL OLE2 PDF HTML PE ELF SWF XMLDOCS HWP3; do
-	# Prepare seed corpus for the type-specific fuzz targets.
-	zip ${OUT}/clamav_scanfile_${type}_fuzzer_seed_corpus.zip ${SRC}/clamav-fuzz-corpus/scantype/${type}/*
-	zip ${OUT}/clamav_scanmap_${type}_fuzzer_seed_corpus.zip ${SRC}/clamav-fuzz-corpus/scantype/${type}/*
+    # Prepare seed corpus for the type-specific fuzz targets.
+    zip ${OUT}/clamav_scanfile_${type}_fuzzer_seed_corpus.zip ${SRC}/clamav-fuzz-corpus/scantype/${type}/*
+    zip ${OUT}/clamav_scanmap_${type}_fuzzer_seed_corpus.zip ${SRC}/clamav-fuzz-corpus/scantype/${type}/*
 
-	# Prepare dictionary for the type-specific fuzz targets (may not exist for all types).
-	cp ${SRC}/clamav-fuzz-corpus/scantype/${type}.dict ${OUT}/clamav_scanfile_${type}_fuzzer.dict 2>/dev/null || :
-	cp ${SRC}/clamav-fuzz-corpus/scantype/${type}.dict ${OUT}/clamav_scanmap_${type}_fuzzer.dict 2>/dev/null || :
+    # Prepare dictionary for the type-specific fuzz targets (may not exist for all types).
+    cp ${SRC}/clamav-fuzz-corpus/scantype/${type}.dict ${OUT}/clamav_scanfile_${type}_fuzzer.dict 2>/dev/null || :
+    cp ${SRC}/clamav-fuzz-corpus/scantype/${type}.dict ${OUT}/clamav_scanmap_${type}_fuzzer.dict 2>/dev/null || :
 
-	# Copy seeds for the generic fuzz target.
-	cp ${SRC}/clamav-fuzz-corpus/scantype/${type}/* ${WORK}/all-scantype-seeds/
+    # Copy seeds for the generic fuzz target.
+    cp ${SRC}/clamav-fuzz-corpus/scantype/${type}/* ${WORK}/all-scantype-seeds/
 done
 
 # Prepare seed corpus for the generic fuzz target.
@@ -61,9 +78,9 @@ rm -r ${WORK}/all-scantype-seeds
 # `dbload`
 # --------
 for type in CDB CFG CRB FP FTM HDB HSB IDB IGN IGN2 LDB MDB MSB NDB PDB WDB YARA; do
-	# Prepare seed corpus for the type-specific fuzz targets.
-	zip ${OUT}/clamav_dbload_${type}_fuzzer_seed_corpus.zip ${SRC}/clamav-fuzz-corpus/database/${type}/*
+    # Prepare seed corpus for the type-specific fuzz targets.
+    zip ${OUT}/clamav_dbload_${type}_fuzzer_seed_corpus.zip ${SRC}/clamav-fuzz-corpus/database/${type}/*
 
-	# Prepare dictionary for the type-specific fuzz targets (may not exist for all types).
-	cp ${SRC}/clamav-fuzz-corpus/database/${type}.dict ${OUT}/clamav_dbload_${type}_fuzzer.dict 2>/dev/null || :
+    # Prepare dictionary for the type-specific fuzz targets (may not exist for all types).
+    cp ${SRC}/clamav-fuzz-corpus/database/${type}.dict ${OUT}/clamav_dbload_${type}_fuzzer.dict 2>/dev/null || :
 done