diff --git a/images/Dockerfile.bottlecap.alpine.compile b/images/Dockerfile.bottlecap.alpine.compile
index 42e5888a8..ac854146f 100644
--- a/images/Dockerfile.bottlecap.alpine.compile
+++ b/images/Dockerfile.bottlecap.alpine.compile
@@ -33,7 +33,9 @@ WORKDIR /tmp/dd/bottlecap
 RUN --mount=type=cache,target=/root/.cargo/git \
     --mount=type=cache,target=/root/.cargo/registry \
     --mount=type=bind,source=.,target=/tmp/dd,rw \
-    --mount=type=cache,target=/tmp/dd/bottlecap/target \
+    # sharing=private gives each concurrent build its own target cache instead of
+    # blocking on cargo's build-directory lock while waiting for a shared mount
+    --mount=type=cache,sharing=private,target=/tmp/dd/bottlecap/target \
     if [ "${FIPS}" = "1" ]; then \
         export FEATURES=fips; \
         if [ "${PLATFORM}" = "aarch64" ]; then \
diff --git a/images/Dockerfile.bottlecap.compile b/images/Dockerfile.bottlecap.compile
index 604026a38..877e6e21e 100644
--- a/images/Dockerfile.bottlecap.compile
+++ b/images/Dockerfile.bottlecap.compile
@@ -34,7 +34,9 @@ WORKDIR /tmp/dd/bottlecap
 RUN --mount=type=cache,target=/usr/local/cargo/git \
     --mount=type=cache,target=/usr/local/cargo/registry \
     --mount=type=bind,source=.,target=/tmp/dd,rw \
-    --mount=type=cache,target=/tmp/dd/bottlecap/target \
+    # sharing=private gives each concurrent build its own target cache instead of
+    # blocking on cargo's build-directory lock while waiting for a shared mount
+    --mount=type=cache,sharing=private,target=/tmp/dd/bottlecap/target \
     if [ "${FIPS}" = "1" ]; then \
         export FEATURES=fips; \
     else \