diff --git a/src/OpenCashFlow.API/Dockerfile b/src/OpenCashFlow.API/Dockerfile
index 934eb58..d4af6fe 100644
--- a/src/OpenCashFlow.API/Dockerfile
+++ b/src/OpenCashFlow.API/Dockerfile
@@ -3,6 +3,12 @@ FROM mcr.microsoft.com/dotnet/aspnet:10.0 AS base
 WORKDIR /app
 EXPOSE 8080
 
+# Npgsql can load the native GSSAPI/Kerberos library during PostgreSQL connection setup.
+# The ASP.NET runtime image is minimal, so install the small runtime dependency explicitly.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends libgssapi-krb5-2 \
+    && rm -rf /var/lib/apt/lists/*
+
 FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
 WORKDIR /src