diff --git a/tools/dockerfile/interoptest/grpc_interop_php/build_interop.sh b/tools/dockerfile/interoptest/grpc_interop_php/build_interop.sh
index 74e2a23a059..8f9a7c3d09e 100755
--- a/tools/dockerfile/interoptest/grpc_interop_php/build_interop.sh
+++ b/tools/dockerfile/interoptest/grpc_interop_php/build_interop.sh
@@ -38,10 +38,11 @@ make -j4 install_c plugins
 
 cd src/php
 
-set +e
-php -d extension=ext/grpc/modules/grpc.so /usr/local/bin/composer install
-while [ $? -ne 0 ]; do
-  php -d extension=ext/grpc/modules/grpc.so /usr/local/bin/composer install
+DONE=0
+for ((i = 0; i < 5; i++)); do
+  php -d extension=ext/grpc/modules/grpc.so /usr/local/bin/composer install && DONE=1
+  [[ "$DONE" == 1 ]] && break
 done
+[[ "$DONE" != 1 ]] && echo "Failed to do composer install" && exit 1
 
 ./bin/generate_proto_php.sh
diff --git a/tools/dockerfile/interoptest/grpc_interop_php7/build_interop.sh b/tools/dockerfile/interoptest/grpc_interop_php7/build_interop.sh
index 70cdffa4cb2..7de17550df2 100755
--- a/tools/dockerfile/interoptest/grpc_interop_php7/build_interop.sh
+++ b/tools/dockerfile/interoptest/grpc_interop_php7/build_interop.sh
@@ -38,10 +38,11 @@ make -j4 install_c plugins
 
 cd src/php
 
-set +e
-php -d extension=ext/grpc/modules/grpc.so /usr/local/bin/composer install
-while [ $? -ne 0 ]; do
-  php -d extension=ext/grpc/modules/grpc.so /usr/local/bin/composer install
+DONE=0
+for ((i = 0; i < 5; i++)); do
+  php -d extension=ext/grpc/modules/grpc.so /usr/local/bin/composer install && DONE=1
+  [[ "$DONE" == 1 ]] && break
 done
+[[ "$DONE" != 1 ]] && echo "Failed to do composer install" && exit 1
 
 ./bin/generate_proto_php.sh