diff --git a/Dockerfile b/Dockerfile
index 30c2019..b4bd1f6 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -89,7 +89,11 @@ RUN set -e; \
       EXCHANGE_DIR="/src/exchange"; \
     fi; \
     if [ "${EXCHANGE_TAR}" = "1" ]; then \
-      cd "${EXCHANGE_DIR}" && autoreconf -fi; \
+      if [ -f "${EXCHANGE_DIR}/configure" ]; then \
+        echo "Using existing configure for Exchange tarball"; \
+      else \
+        cd "${EXCHANGE_DIR}" && autoreconf -fi; \
+      fi; \
     else \
       if [ ! -f "${EXCHANGE_DIR}/configure" ]; then \
         cd "${EXCHANGE_DIR}" && env GNUNET_PREFIX=/usr ./bootstrap; \
@@ -120,7 +124,11 @@ RUN set -e; \
       MERCHANT_DIR="/src/merchant"; \
     fi; \
     if [ "${MERCHANT_TAR}" = "1" ]; then \
-      cd "${MERCHANT_DIR}" && autoreconf -fi; \
+      if [ -f "${MERCHANT_DIR}/configure" ]; then \
+        echo "Using existing configure for Merchant tarball"; \
+      else \
+        cd "${MERCHANT_DIR}" && autoreconf -fi; \
+      fi; \
     else \
       if [ ! -f "${MERCHANT_DIR}/configure" ]; then \
         cd "${MERCHANT_DIR}" && env GNUNET_PREFIX=/usr ./bootstrap; \