diff --git a/EXR/ReadEXR.cpp b/EXR/ReadEXR.cpp
index 85aeb69..103eaf5 100644
--- a/EXR/ReadEXR.cpp
+++ b/EXR/ReadEXR.cpp
@@ -38,15 +38,33 @@
 
 #include "ofxsMacros.h"
 
+// Check OpenEXR version to determine header locations
+#include <OpenEXR/OpenEXRConfig.h>
+#define COMBINED_OPENEXR_VERSION ((10000*OPENEXR_VERSION_MAJOR) + \
+                                  (100*OPENEXR_VERSION_MINOR) + \
+                                  OPENEXR_VERSION_PATCH)
+
 GCC_DIAG_OFF(deprecated)
-#include <IlmThreadPool.h>
-#include <ImathBox.h>
-#include <ImfChannelList.h>
-#include <ImfCompression.h>
-#include <ImfFrameBuffer.h>
-#include <ImfHeader.h>
-#include <ImfInputFile.h>
-#include <ImfPixelType.h>
+#if COMBINED_OPENEXR_VERSION >= 20599 /* 2.5.99: pre-3.0 */
+#   include <OpenEXR/IlmThreadPool.h>
+#   include <Imath/ImathBox.h>
+#   include <OpenEXR/ImfChannelList.h>
+#   include <OpenEXR/ImfCompression.h>
+#   include <OpenEXR/ImfFrameBuffer.h>
+#   include <OpenEXR/ImfHeader.h>
+#   include <OpenEXR/ImfInputFile.h>
+#   include <OpenEXR/ImfPixelType.h>
+#else
+    // OpenEXR 2.x, use the old locations
+#   include <IlmThreadPool.h>
+#   include <ImathBox.h>
+#   include <ImfChannelList.h>
+#   include <ImfCompression.h>
+#   include <ImfFrameBuffer.h>
+#   include <ImfHeader.h>
+#   include <ImfInputFile.h>
+#   include <ImfPixelType.h>
+#endif
 GCC_DIAG_ON(deprecated)
 
 #ifdef OFX_IO_MT_EXR
diff --git a/EXR/WriteEXR.cpp b/EXR/WriteEXR.cpp
index 6711b87..b03c69f 100644
--- a/EXR/WriteEXR.cpp
+++ b/EXR/WriteEXR.cpp
@@ -27,16 +27,33 @@
 #include "ofxsFileOpen.h"
 #include "ofxsMacros.h"
 
+#include <OpenEXR/OpenEXRConfig.h>
+#define COMBINED_OPENEXR_VERSION ((10000*OPENEXR_VERSION_MAJOR) + \
+                                  (100*OPENEXR_VERSION_MINOR) + \
+                                  OPENEXR_VERSION_PATCH)
+
 GCC_DIAG_OFF(deprecated)
-#include <IlmThreadPool.h>
-#include <ImathBox.h>
-#include <ImfArray.h>
-#include <ImfChannelList.h>
-#include <ImfCompression.h>
-#include <ImfFrameBuffer.h>
-#include <ImfHeader.h>
-#include <ImfOutputFile.h>
-#include <half.h>
+#if COMBINED_OPENEXR_VERSION >= 20599 /* 2.5.99: pre-3.0 */
+#   include <OpenEXR/IlmThreadPool.h>
+#   include <Imath/ImathBox.h>
+#   include <OpenEXR/ImfArray.h>
+#   include <OpenEXR/ImfChannelList.h>
+#   include <OpenEXR/ImfCompression.h>
+#   include <OpenEXR/ImfFrameBuffer.h>
+#   include <OpenEXR/ImfHeader.h>
+#   include <OpenEXR/ImfOutputFile.h>
+#   include <Imath/half.h>
+#else
+    // OpenEXR 2.x, use the old locations
+#   include <IlmThreadPool.h>
+#   include <ImathBox.h>
+#   include <ImfArray.h>
+#   include <ImfChannelList.h>
+#   include <ImfCompression.h>
+#   include <ImfFrameBuffer.h>
+#   include <ImfHeader.h>
+#   include <ImfOutputFile.h>
+#   include <half.h>
 GCC_DIAG_ON(deprecated)
 
 #include "GenericOCIO.h"
@@ -267,6 +284,10 @@ WriteEXRPlugin::encode(const string& filename,
             } else {
                 Imf_::Array2D<half> halfwriterow(pixelDataNComps, bounds.x2 - bounds.x1);
 
+#if COMBINED_OPENEXR_VERSION >= 20599 /* 2.5.99: pre-3.0 */
+                using Imath::half;
+#endif
+
                 for (int chan = 0; chan < pixelDataNComps; ++chan) {
                     fbuf.insert(chanNames[chan],
                                 Imf_::Slice(Imf_::HALF,
diff --git a/Makefile.master b/Makefile.master
index 8b27df8..ddd0420 100644
--- a/Makefile.master
+++ b/Makefile.master
@@ -24,9 +24,12 @@ endif
 # OpenEXR
 # OpenImageIO includes OpenEXR as #include <OpenEXR/ImathVec.h>, to we also add the
 # include dir itself to avoid confusion with a system-installed OpenEXR.
-# OpenEXR 2 has IlmBase, OpenEXR 3 has Imath, so we ask for both, but it will always cause harmless errors.
-OPENEXR_CXXFLAGS = -I`pkg-config --variable=prefix OpenEXR`/include `pkg-config --cflags IlmBase 2>/dev/null` `pkg-config --cflags Imath 2>/dev/null` `pkg-config --cflags OpenEXR`
-OPENEXR_LINKFLAGS =`pkg-config --libs IlmBase 2>/dev/null` `pkg-config --libs Imath 2>/dev/null` `pkg-config --libs OpenEXR`
+# OpenEXR 2 has IlmBase, OpenEXR 3 has Imath, so we ask for both.
+# Try Imath first (OpenEXR 3.x), then fallback to IlmBase (OpenEXR 2.x)
+IMATH_CXXFLAGS := $(shell pkg-config --cflags Imath 2>/dev/null || pkg-config --cflags IlmBase 2>/dev/null)
+IMATH_LINKFLAGS := $(shell pkg-config --libs Imath 2>/dev/null || pkg-config --libs IlmBase 2>/dev/null)
+OPENEXR_CXXFLAGS = -I`pkg-config --variable=prefix OpenEXR`/include $(IMATH_CXXFLAGS) `pkg-config --cflags OpenEXR`
+OPENEXR_LINKFLAGS = $(IMATH_LINKFLAGS) `pkg-config --libs OpenEXR`
 # Uncomment the following line to enable multithreaded EXR reading (untested, and probably does not make sense)
 #OPENEXR_CXXFLAGS += -DOFX_IO_MT_EXR
 
@@ -37,7 +40,7 @@ FFMPEG_LINKFLAGS = `pkg-config --libs libavformat libavcodec libswscale libavuti
 FFMPEG_CXXFLAGS += -DOFX_IO_MT_FFMPEG
 
 # OpenImageIO
-OIIO_CXXFLAGS = $(OCIO_CXXFLAGS) `pkg-config --cflags OpenImageIO` $(OPENEXR_CFLAGS) -DOFX_IO_USING_LIBRAW `pkg-config --cflags libraw_r libwebp libtiff-4 libopenjp2 libpng`
+OIIO_CXXFLAGS = $(OCIO_CXXFLAGS) `pkg-config --cflags OpenImageIO` $(OPENEXR_CXXFLAGS) -DOFX_IO_USING_LIBRAW `pkg-config --cflags libraw_r libwebp libtiff-4 libopenjp2 libpng`
 OIIO_LINKFLAGS = $(OCIO_LINKFLAGS) `pkg-config --libs OpenImageIO` $(OPENEXR_LINKFLAGS) `pkg-config --libs libraw_r libwebp libtiff-4 libopenjp2 libpng`
 ifeq ($(OS),Linux)
 # libraw_r may be in a separate directory for licence reasons (eg in the Natron SDK)