diff --git a/.circleci/config.yml b/.circleci/config.yml
index 062c91fb8..0d4cf3c3d 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -75,7 +75,7 @@ jobs:
       - image: circleci/python:3.6.12-stretch
     environment:
       CIBW_SKIP: "pp* cp27-* cp34-* cp35-* cp36-* *i686"
-      CIBW_BEFORE_BUILD_LINUX: curl -OsL https://gitlab.com/libeigen/eigen/-/archive/3.3.7/eigen-3.3.7.tar.gz && tar xzf eigen-3.3.7.tar.gz eigen-3.3.7/Eigen --strip-components 1 && cp -rf Eigen {project}/include && pip install numpy~=1.19 scipy cython
+      CIBW_BEFORE_BUILD_LINUX: curl -OsL https://gitlab.com/libeigen/eigen/-/archive/3.3.7/eigen-3.3.7.tar.gz && tar xzf eigen-3.3.7.tar.gz eigen-3.3.7/Eigen --strip-components 1 && cp -rf Eigen {project}/include && pip install numpy==1.19.5 scipy cython
       CIBW_TEST_REQUIRES: numpy scipy pytest pytest-cov pytest-randomly
       CIBW_TEST_COMMAND: python -m pytest --randomly-seed=137 {project}/thewalrus
     steps:
@@ -110,7 +110,7 @@ jobs:
       CIBW_SKIP: "pp* cp27-* cp34-* cp35-* cp36-* *i686"
       CIBW_ENVIRONMENT: "MACOSX_DEPLOYMENT_TARGET=10.9"
 
-      CIBW_BEFORE_BUILD_MACOS: brew install gmp gcc eigen libomp; pip install numpy~=1.19 scipy cython
+      CIBW_BEFORE_BUILD_MACOS: brew install gmp gcc eigen libomp; pip install numpy==1.19.5 scipy cython
       CIBW_TEST_REQUIRES: numpy scipy pytest pytest-cov pytest-randomly
       CIBW_TEST_COMMAND: python -m pytest --randomly-seed=137 {project}/thewalrus
     steps:
diff --git a/.github/CHANGELOG.md b/.github/CHANGELOG.md
index ce1bfb138..e045276dd 100644
--- a/.github/CHANGELOG.md
+++ b/.github/CHANGELOG.md
@@ -1,17 +1,17 @@
-# Version 0.16.0-dev
-
-### New features
-
-### Improvements
+# Version 0.15.1
 
 ### Bug fixes
 
-### Breaking changes
+* Builds The Walrus binaries against an older version of NumPy, to avoid
+  a breaking ABI change in NumPy 1.20.
+  [#240](https://github.com/XanaduAI/thewalrus/pull/240)
 
 ### Contributors
 
 This release contains contributions from (in alphabetical order):
 
+Josh Izaac
+
 ---
 
 # Version 0.15.0
diff --git a/appveyor.yml b/appveyor.yml
index 7a3ff9113..7eacb17ef 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -4,7 +4,7 @@ environment:
       APPVEYOR_SKIP_FINALIZE_ON_EXIT: true
       EIGEN_INCLUDE_DIR: C:\eigen-3.3.7\
       TEST_TIMEOUT: 1000
-      CIBW_BEFORE_BUILD: pip install numpy~=1.19 scipy cython
+      CIBW_BEFORE_BUILD: pip install numpy==1.19.5 scipy cython
       CIBW_SKIP: "cp27-* cp33-* cp34-* cp35-* cp36-* *win32"
       CIBW_TEST_REQUIRES: "numpy scipy pytest pytest-cov pytest-randomly"
       CIBW_TEST_COMMAND: "python -m pytest --randomly-seed=137 {project}/thewalrus"
diff --git a/thewalrus/_version.py b/thewalrus/_version.py
index 047c00a11..aedb2e1a5 100644
--- a/thewalrus/_version.py
+++ b/thewalrus/_version.py
@@ -16,4 +16,4 @@
    Version number (major.minor.patch[-label])
 """
 
-__version__ = "0.15.0"
+__version__ = "0.15.1"