diff --git a/Makefile.am b/Makefile.am
index 5b58dc4d..af77d2ae 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -38,12 +38,7 @@ AM_CPPFLAGS += \
   $(LTDLINCL) \
   -I$(top_srcdir)/src \
   -I$(top_srcdir)/src/compat \
-  -I$(top_srcdir)/src/libmpg123 \
-  -I$(top_srcdir)/src/libsyn123 \
-  -I$(top_srcdir)/src/libout123 \
-  -I$(top_builddir)/src/libmpg123 \
-  -I$(top_builddir)/src/libsyn123 \
-  -I$(top_builddir)/src/libout123
+  -I$(top_srcdir)/src/common
 
 # Include Make modules from subdirectories.
 include src/Makemodule.am
@@ -53,15 +48,18 @@ if NEED_MAINLIB
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = 
 
-# Stuff from this directory.
+# Pkg-config files and library includes.
 if BUILD_LIBMPG123
 pkgconfig_DATA += libmpg123.pc
+AM_CPPFLAGS += -I$(top_srcdir)/src/libmpg123
 endif
 if BUILD_LIBOUT123
 pkgconfig_DATA += libout123.pc
+AM_CPPFLAGS += -I$(top_srcdir)/src/libout123
 endif
 if BUILD_LIBSYN123
 pkgconfig_DATA += libsyn123.pc
+AM_CPPFLAGS += -I$(top_srcdir)/src/libsyn123
 endif
 endif
 
diff --git a/NEWS b/NEWS
index 01ee7231..c353896f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,7 @@
 1.32.4
 ------
 - build:
+-- Reorganize shared headers.
 -- Group C99 feature checks and make several standard headers
    mandatory.
 -- Get rid of SIZE_P, OFF_P and friends.
diff --git a/ports/cmake/src/CMakeLists.txt b/ports/cmake/src/CMakeLists.txt
index 97220171..bc65c53e 100644
--- a/ports/cmake/src/CMakeLists.txt
+++ b/ports/cmake/src/CMakeLists.txt
@@ -342,6 +342,7 @@ include_directories(
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../src/"
     "${CMAKE_CURRENT_BINARY_DIR}"
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../src/compat"
+    "${CMAKE_CURRENT_SOURCE_DIR}/../../../src/common"
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../src/libsyn123"
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../src/libout123"
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../src/libmpg123")
diff --git a/src/Makemodule.am b/src/Makemodule.am
index b894a8aa..48632b57 100644
--- a/src/Makemodule.am
+++ b/src/Makemodule.am
@@ -2,6 +2,7 @@
 
 include src/tests/Makemodule.am
 include src/compat/Makemodule.am
+include src/common/Makemodule.am
 if NEED_LIB
 include src/libout123/Makemodule.am
 if NEED_MAINLIB
diff --git a/src/common/Makemodule.am b/src/common/Makemodule.am
new file mode 100644
index 00000000..4a31b96b
--- /dev/null
+++ b/src/common/Makemodule.am
@@ -0,0 +1,7 @@
+# common headers shared between subprojects
+EXTRA_DIST += \
+  src/common/abi_align.h \
+  src/common/debug.h \
+  src/common/sample.h \
+  src/common/swap_bytes_impl.h \
+  src/common/true.h
diff --git a/src/libmpg123/abi_align.h b/src/common/abi_align.h
similarity index 100%
rename from src/libmpg123/abi_align.h
rename to src/common/abi_align.h
diff --git a/src/libmpg123/debug.h b/src/common/debug.h
similarity index 100%
rename from src/libmpg123/debug.h
rename to src/common/debug.h
diff --git a/src/libmpg123/sample.h b/src/common/sample.h
similarity index 100%
rename from src/libmpg123/sample.h
rename to src/common/sample.h
diff --git a/src/libmpg123/swap_bytes_impl.h b/src/common/swap_bytes_impl.h
similarity index 100%
rename from src/libmpg123/swap_bytes_impl.h
rename to src/common/swap_bytes_impl.h
diff --git a/src/libmpg123/true.h b/src/common/true.h
similarity index 100%
rename from src/libmpg123/true.h
rename to src/common/true.h
diff --git a/src/libmpg123/Makemodule.am b/src/libmpg123/Makemodule.am
index 48e3820f..2557154a 100644
--- a/src/libmpg123/Makemodule.am
+++ b/src/libmpg123/Makemodule.am
@@ -45,12 +45,9 @@ src_libmpg123_libmpg123_la_SOURCES = \
   src/libmpg123/parse.h \
   src/libmpg123/frame.c \
   src/libmpg123/format.c \
-  src/libmpg123/swap_bytes_impl.h \
   src/libmpg123/frame.h \
   src/libmpg123/reader.h \
-  src/libmpg123/debug.h \
   src/libmpg123/decode.h \
-  src/libmpg123/sample.h \
   src/libmpg123/dct64.c \
   src/libmpg123/synth.h \
   src/libmpg123/synth_mono.h \
@@ -63,7 +60,6 @@ src_libmpg123_libmpg123_la_SOURCES = \
   src/libmpg123/icy2utf8.h \
   src/libmpg123/id3.h \
   src/libmpg123/id3.c \
-  src/libmpg123/true.h \
   src/libmpg123/getbits.h \
   src/libmpg123/optimize.h \
   src/libmpg123/optimize.c \
@@ -74,7 +70,6 @@ src_libmpg123_libmpg123_la_SOURCES = \
   src/libmpg123/libmpg123.c \
   src/libmpg123/gapless.h \
   src/libmpg123/mpg123lib_intern.h \
-  src/libmpg123/abi_align.h \
   src/libmpg123/mangle.h \
   src/libmpg123/getcpuflags.h \
   src/libmpg123/index.h \