diff --git a/travis/travis-base-386.Dockerfile b/travis/travis-base-386.Dockerfile
index fab1a48f7..8996e029f 100644
--- a/travis/travis-base-386.Dockerfile
+++ b/travis/travis-base-386.Dockerfile
@@ -26,3 +26,8 @@ COPY debian/control /usr/src/i3-debian-packaging/control
 RUN linux32 apt-get update && \
     DEBIAN_FRONTEND=noninteractive mk-build-deps --install --remove --tool 'apt-get --no-install-recommends -y' /usr/src/i3-debian-packaging/control && \
     rm -rf /var/lib/apt/lists/*
+
+# The user outside of Docker (GitHub Actions CI runner) and inside of Docker
+# (root) are different, and newer versions of git error out in that scenario.
+# To fix this, explicitly configure /usr/src/i3 as a safe directory:
+RUN git config --global --add safe.directory /usr/src/i3
diff --git a/travis/travis-base-ubuntu-386.Dockerfile b/travis/travis-base-ubuntu-386.Dockerfile
index a66d58a2c..4a41fe3e7 100644
--- a/travis/travis-base-ubuntu-386.Dockerfile
+++ b/travis/travis-base-ubuntu-386.Dockerfile
@@ -26,3 +26,8 @@ COPY debian/control /usr/src/i3-debian-packaging/control
 RUN linux32 apt-get update && \
     DEBIAN_FRONTEND=noninteractive mk-build-deps --install --remove --tool 'apt-get --no-install-recommends -y' /usr/src/i3-debian-packaging/control && \
     rm -rf /var/lib/apt/lists/*
+
+# The user outside of Docker (GitHub Actions CI runner) and inside of Docker
+# (root) are different, and newer versions of git error out in that scenario.
+# To fix this, explicitly configure /usr/src/i3 as a safe directory:
+RUN git config --global --add safe.directory /usr/src/i3
diff --git a/travis/travis-base-ubuntu.Dockerfile b/travis/travis-base-ubuntu.Dockerfile
index 9ee9d3554..8523b92ca 100644
--- a/travis/travis-base-ubuntu.Dockerfile
+++ b/travis/travis-base-ubuntu.Dockerfile
@@ -27,3 +27,8 @@ COPY debian/control /usr/src/i3-debian-packaging/control
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive mk-build-deps --install --remove --tool 'apt-get --no-install-recommends -y' /usr/src/i3-debian-packaging/control && \
     rm -rf /var/lib/apt/lists/*
+
+# The user outside of Docker (GitHub Actions CI runner) and inside of Docker
+# (root) are different, and newer versions of git error out in that scenario.
+# To fix this, explicitly configure /usr/src/i3 as a safe directory:
+RUN git config --global --add safe.directory /usr/src/i3
diff --git a/travis/travis-base.Dockerfile b/travis/travis-base.Dockerfile
index da5531ffa..52ae0656a 100644
--- a/travis/travis-base.Dockerfile
+++ b/travis/travis-base.Dockerfile
@@ -27,3 +27,8 @@ COPY debian/changelog /usr/src/i3-debian-packaging/changelog
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive mk-build-deps --install --remove --tool 'apt-get --no-install-recommends -y' /usr/src/i3-debian-packaging/control && \
     rm -rf /var/lib/apt/lists/*
+
+# The user outside of Docker (GitHub Actions CI runner) and inside of Docker
+# (root) are different, and newer versions of git error out in that scenario.
+# To fix this, explicitly configure /usr/src/i3 as a safe directory:
+RUN git config --global --add safe.directory /usr/src/i3