diff --git a/.gitignore b/.gitignore
index fa5c39f..2720fc2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,9 +18,3 @@
 /alembic-1.8.2.tar.gz
 /alembic-1.8.3.tar.gz
 /alembic-1.8.4.tar.gz
-/alembic-1.8.5.tar.gz
-/alembic-1.8.6.tar.gz
-/alembic-1.8.7.tar.gz
-/alembic-1.8.8.tar.gz
-/alembic-1.8.9.tar.gz
-/alembic-1.8.10.tar.gz
diff --git a/alembic-1.7.11-0002-Find-IlmBase-by-setting-a-proper-ILMBASE_ROOT-value.patch b/alembic-1.7.11-0002-Find-IlmBase-by-setting-a-proper-ILMBASE_ROOT-value.patch
new file mode 100644
index 0000000..c561e26
--- /dev/null
+++ b/alembic-1.7.11-0002-Find-IlmBase-by-setting-a-proper-ILMBASE_ROOT-value.patch
@@ -0,0 +1,72 @@
+From 60bbcde225f3c28a36d8643c451509d9deb09222 Mon Sep 17 00:00:00 2001
+From: Bernd Waibel <waebbl@gmail.com>
+Date: Sat, 15 Jun 2019 13:34:09 +0200
+Subject: [PATCH 2/5] Find IlmBase by setting a proper ILMBASE_ROOT value and
+ by using pkg-config to determine the installed ilmbase version, instead of
+ using the cmake STRINGS command.
+
+Signed-off-by: Bernd Waibel <waebbl@gmail.com>
+---
+ cmake/Modules/FindIlmBase.cmake   | 18 +++++++++++++++++-
+ cmake/Modules/FindPyIlmBase.cmake |  2 +-
+ 2 files changed, 18 insertions(+), 2 deletions(-)
+
+diff --git a/cmake/Modules/FindIlmBase.cmake b/cmake/Modules/FindIlmBase.cmake
+index 679a02f..0fe2b1a 100644
+--- a/cmake/Modules/FindIlmBase.cmake
++++ b/cmake/Modules/FindIlmBase.cmake
+@@ -52,7 +52,7 @@ IF(NOT DEFINED ILMBASE_ROOT)
+           SET( ALEMBIC_ILMBASE_ROOT NOTFOUND )
+         ELSE()
+           # TODO: set to default install path when shipping out
+-          SET( ALEMBIC_ILMBASE_ROOT "/usr/local/ilmbase-1.0.1/" )
++          SET( ALEMBIC_ILMBASE_ROOT "/usr" )
+         ENDIF()
+     ELSE()
+         IF ( ${WINDOWS} )
+@@ -87,6 +87,21 @@ SET(_ilmbase_SEARCH_DIRS
+     /usr/freeware
+ )
+ 
++# use pkg-config to determine the correct version
++include(FindPkgConfig)
++IF(PKG_CONFIG_FOUND)
++    PKG_CHECK_MODULES(PC_ILMBASE QUIET IlmBase)
++    IF(PC_ILMBASE_FOUND)
++        SET(ILMBASE_VERSION ${PC_ILMBASE_VERSION})
++        SET(ALEMBIC_ILMBASE_INCLUDE_DIRECTORY ${PC_ILMBASE_INCLUDE_DIRS})
++        STRING(REGEX MATCH "-lHalf" ALEMBIC_ILMBASE_HALF_LIB ${PC_ILMBASE_LDFLAGS})
++        STRING(REGEX MATCH "-lIex" ALEMBIC_ILMBASE_IEX_LIB ${PC_ILMBASE_LDFLAGS})
++        STRING(REGEX MATCH "-lIexMath" ALEMBIC_ILMBASE_IEXMATH_LIB ${PC_ILMBASE_LDFLAGS})
++        STRING(REGEX MATCH "-lIlmThread" ALEMBIC_ILMBASE_ILMTHREAD_LIB ${PC_ILMBASE_LDFLAGS})
++        String(REGEX MATCH "-lImath" ALEMBIC_ILMBASE_IMATH_LIB ${PC_ILMBASE_LDFLAGS})
++    ENDIF()
++ELSE(PKG_CONFIG_FOUND)
++
+ FIND_PATH(ILMBASE_INCLUDE_DIR
+   NAMES
+     IlmBaseConfig.h
+@@ -179,6 +194,7 @@ IF ( ${ALEMBIC_ILMBASE_INCLUDE_DIRECTORY} STREQUAL "ALEMBIC_ILMBASE_INCLUDE_DIRE
+   MESSAGE( FATAL_ERROR "ilmbase header files not found, required: ALEMBIC_ILMBASE_ROOT: ${ALEMBIC_ILMBASE_ROOT}" )
+ ENDIF()
+ 
++ENDIF(PKG_CONFIG_FOUND)
+ 
+ MESSAGE( STATUS "ILMBASE INCLUDE PATH: ${ALEMBIC_ILMBASE_INCLUDE_DIRECTORY}" )
+ MESSAGE( STATUS "HALF LIB: ${ALEMBIC_ILMBASE_HALF_LIB}" )
+diff --git a/cmake/Modules/FindPyIlmBase.cmake b/cmake/Modules/FindPyIlmBase.cmake
+index d55f8d3..b5f3cb5 100644
+--- a/cmake/Modules/FindPyIlmBase.cmake
++++ b/cmake/Modules/FindPyIlmBase.cmake
+@@ -44,7 +44,7 @@ ELSE()
+               SET(ALEMBIC_PYILMBASE_ROOT NOTFOUND)
+             ELSE()
+               # TODO: set to default install path when shipping out
+-              SET(ALEMBIC_PYILMBASE_ROOT "/usr/local/pyilmbase/")
++              SET(ALEMBIC_PYILMBASE_ROOT "/usr")
+             ENDIF()
+         ELSE()
+             IF (${WINDOWS})
+-- 
+2.22.0
+
diff --git a/alembic.spec b/alembic.spec
index 4f9b621..d2a21bb 100644
--- a/alembic.spec
+++ b/alembic.spec
@@ -5,18 +5,30 @@
 # Python Module
 
 Name:           alembic
-Version:        1.8.10
+Version:        1.8.4
 Release:        %autorelease
 Summary:        Open framework for storing and sharing scene data
-License:        BSD-3-Clause AND BSL-1.0
+License:        BSD
 URL:            http://alembic.io/
+
 Source0:        https://github.com/%{name}/%{name}/archive/%{version}%{?prerelease}.tar.gz#/%{name}-%{version}%{?prerelease}.tar.gz
 
+# Use patch from Gentoo fixing iblmbase root path
+# https://gitweb.gentoo.org/repo/gentoo.git/tree/media-gfx/alembic/files/alembic-1.7.11-0002-Find-IlmBase-by-setting-a-proper-ILMBASE_ROOT-value.patch?id=953b3b21db55df987dd8006dcdec19e945294d98
+Patch0:         alembic-1.7.11-0002-Find-IlmBase-by-setting-a-proper-ILMBASE_ROOT-value.patch 
 BuildRequires:  boost-devel
 BuildRequires:  cmake >= 3.13
-BuildRequires:  gcc-c++
+BuildRequires:	gcc-c++
 BuildRequires:  hdf5-devel
+
+# Per https://github.com/alembic/alembic/blob/master/README.txt
+# alembic actually needs ilmbase, not OpenEXR.
+# As of OpenEXR 3.x Imath is now a standalone library.
+%if 0%{?fedora} > 34
 BuildRequires:  cmake(Imath)
+%else
+BuildRequires:  pkgconfig(IlmBase)
+%endif
 BuildRequires:  pkgconfig(zlib)
 
 %description
@@ -38,9 +50,8 @@ rendered image data.
 
 %package        devel
 Summary:        Development files for %{name}
-Requires:       %{name}-libs%{?_isa} = %{version}-%{release}
+Requires:       %{name}%{?_isa} = %{version}-%{release}
 Requires:       cmake%{?_isa}
-Requires:       imath-devel%{?_isa}
 
 %description    devel
 The %{name}-devel package contains libraries and header files for developing
diff --git a/sources b/sources
index c42304e..b549d5a 100644
--- a/sources
+++ b/sources
@@ -1 +1 @@
-SHA512 (alembic-1.8.10.tar.gz) = 0be292e9d75560891d38129eb2672c55475b29b33f265dd51396dfa7b530c92ac6dfdb05a4432ad1b6919e2c151068560eb04efb8d9b0c2a14f77ab489d3542c
+SHA512 (alembic-1.8.4.tar.gz) = 2473f4b9afe3fddbd2d0477bdc85d93697e413410253a7f7f0f030fba919dfb63dabd2d2d13829f59f3f901643ab842d230a9f08fb667e2c16cef0e751a8a687