diff --git a/Dockerfile b/Dockerfile
index c79dee1..b47012e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,10 +9,16 @@ ENV DISABLE_ORGANIZATION=false
 ENV PDF_DEMO_LINK=true
 
 RUN apt update && \
-    apt install -y gettext-base librsvg2-bin pdftk imagemagick potrace ghostscript && \
+    apt install -y locales gettext-base librsvg2-bin pdftk imagemagick potrace ghostscript && \
     docker-php-ext-install gettext && \
     rm -rf /var/lib/apt/lists/*
 
+RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && \
+    locale-gen
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
 COPY . /usr/local/signaturepdf
 
 RUN envsubst < /usr/local/signaturepdf/config/php.ini > /usr/local/etc/php/conf.d/uploads.ini && \