diff --git a/Makefile.rules b/Makefile.rules
index 5a5f61fb33..f69cf6e172 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -192,13 +192,13 @@ SYSINFO_CPPFLAGS =
 GAP_CPPFLAGS += -I$(builddir)/build
 SYSINFO_CPPFLAGS += -I$(abs_builddir)/build
 
-# The other source files are relative to the srcdir
-GAP_CPPFLAGS += -I$(srcdir)/src
-SYSINFO_CPPFLAGS += -I$(abs_srcdir)/src
-
-# For backwards compatibility with certain packages and their kernel
-# extensions, also add the root of the srcdir to the package CPPFLAGS
-SYSINFO_CPPFLAGS += -I$(abs_srcdir)
+# The other source files are bundled and exported through the few headers in
+# the `src/extra/` directory. We deliberately do not add `src/` itself as an
+# include directory to improve portability: it helps avoid clashes between our
+# headers and system headers (e.g. for `io.h` this would otherwise be a
+# problem on MinGW).
+GAP_CPPFLAGS += -I$(srcdir)/src/extra
+SYSINFO_CPPFLAGS += -I$(abs_srcdir)/src/extra
 
 # Add GAP_DEFINES (from autoconf, contains -D flags)
 GAP_CPPFLAGS += $(GAP_DEFINES)
@@ -513,10 +513,11 @@ libgap$(SHLIB_EXT): $(LIBGAP_FULL)
 gap$(EXEEXT): build/obj/src/main.c.o $(OBJS) cnf/GAP-LDFLAGS cnf/GAP-LIBS cnf/GAP-OBJS
 	$(QUIET_LINK)$(LINK) $(GAP_LDFLAGS) $< $(OBJS) $(GAP_LIBS) -o $@
 
-# generate a modified copy of main.c for use by the `gap-install` binary
-build/main.c: src/main.c config.status
+# generate a special main.c which sets SYS_DEFAULT_PATHS and then includes
+# regular main.c; this is used to build the `gap-install` binary
+build/main.c: sysinfo.gap
 	@echo "#define SYS_DEFAULT_PATHS \"$(libdir)/gap;$(datarootdir)/gap\"" > $@
-	@cat $< >> $@
+	@echo "#include \"$(abs_srcdir)/src/main.c\"" >> $@
 
 # build rule for the gap executable used by the `install-bin` target
 build/gap-install: build/obj/build/main.c.o libgap$(SHLIB_EXT) cnf/GAP-LDFLAGS cnf/GAP-LIBS cnf/GAP-OBJS
@@ -542,7 +543,7 @@ build/c_%.c: $(srcdir)/lib/%.g build/gap-nocomp$(EXEEXT)
 # The "ffdata" target regenerates build/ffdata.{c,h} using etc/ffgen.c
 ########################################################################
 
-ffgen: $(srcdir)/etc/ffgen.c src/common.h build/config.h
+ffgen: $(srcdir)/etc/ffgen.c build/config.h
 	$(QUIET_CC)$(CC) -Wall -Wextra $(GAP_CPPFLAGS) $< -o $@
 
 build/ffdata.h build/ffdata.c: ffgen
@@ -669,7 +670,7 @@ install-gaproot: install-dirs CITATION
 
 
 # the following lines adjust variables for the installed sysinfo.gap
-install-sysinfo: SYSINFO_CPPFLAGS = -I${includedir}/gap -I${includedir} $(GAP_DEFINES)
+install-sysinfo: SYSINFO_CPPFLAGS = -I${includedir}/gap/extra $(GAP_DEFINES)
 install-sysinfo: SYSINFO_LDFLAGS = $(ABI_CFLAGS)
 install-sysinfo: SYSINFO_GAP = $(bindir)/gap
 install-sysinfo: SYSINFO_GAC = $(bindir)/gac
@@ -686,6 +687,8 @@ install-headers: $(FFDATA_H) build/version.h
 	$(INSTALL) -m 0644 $(builddir)/build/version.h $(DESTDIR)$(includedir)/gap
 	$(INSTALL) -d -m 0755 $(DESTDIR)$(includedir)/gap/hpc
 	$(INSTALL) -m 0644 $(srcdir)/src/hpc/*.h $(DESTDIR)$(includedir)/gap/hpc
+	$(INSTALL) -d -m 0755 $(DESTDIR)$(includedir)/gap/extra
+	$(INSTALL) -m 0644 $(srcdir)/src/extra/*.h $(DESTDIR)$(includedir)/gap/extra
 
 install-libgap: install-dirs $(LIBGAP_FULL) libgap.pc
 	$(INSTALL) -d -m 0755 $(DESTDIR)$(libdir)
diff --git a/etc/ffgen.c b/etc/ffgen.c
index 0b225cad96..c002e9a39d 100644
--- a/etc/ffgen.c
+++ b/etc/ffgen.c
@@ -62,7 +62,7 @@ void emit_code(FILE * dest, int header)
         fprintf(dest, "#ifndef GAP_FFDATA_H\n");
         fprintf(dest, "#define GAP_FFDATA_H\n");
         fprintf(dest, "\n");
-        fprintf(dest, "#include \"common.h\"\n");
+        fprintf(dest, "#include <stdint.h>\n");
         fprintf(dest, "\n");
         fprintf(dest, "enum {\n");
         fprintf(dest, "    NUM_SHORT_FINITE_FIELDS = %d,\n", num_ff);
@@ -72,18 +72,18 @@ void emit_code(FILE * dest, int header)
         fprintf(dest, "    VAL_BITS_FFE = %d\n", needed_bits(MAX_FF - 1));
         fprintf(dest, "};\n");
         fprintf(dest, "\n");
-        fprintf(dest, "extern const UInt4 SizeFF[NUM_SHORT_FINITE_FIELDS+1];\n");
-        fprintf(dest, "extern const UInt1 DegrFF[NUM_SHORT_FINITE_FIELDS+1];\n");
-        fprintf(dest, "extern const UInt4 CharFF[NUM_SHORT_FINITE_FIELDS+1];\n");
+        fprintf(dest, "extern const uint32_t SizeFF[NUM_SHORT_FINITE_FIELDS+1];\n");
+        fprintf(dest, "extern const uint8_t DegrFF[NUM_SHORT_FINITE_FIELDS+1];\n");
+        fprintf(dest, "extern const uint32_t CharFF[NUM_SHORT_FINITE_FIELDS+1];\n");
         fprintf(dest, "\n");
         if (num_ff < 65536)
-            fprintf(dest, "typedef UInt2 FF;\n");
+            fprintf(dest, "typedef uint16_t FF;\n");
         else
-            fprintf(dest, "typedef UInt4 FF;\n");
+            fprintf(dest, "typedef uint32_t FF;\n");
         if (MAX_FF <= 65536)
-            fprintf(dest, "typedef UInt2 FFV;\n");
+            fprintf(dest, "typedef uint16_t FFV;\n");
         else
-            fprintf(dest, "typedef UInt4 FFV;\n");
+            fprintf(dest, "typedef uint32_t FFV;\n");
         fprintf(dest, "\n");
         fprintf(dest, "#endif // GAP_FFDATA_H\n");
     }
@@ -94,7 +94,7 @@ void emit_code(FILE * dest, int header)
         fprintf(dest, " * to find them. Indices start at 1.\n");
         fprintf(dest, " */\n");
         fprintf(dest, "\n");
-        fprintf(dest, "const UInt1 DegrFF[NUM_SHORT_FINITE_FIELDS+1] = {\n");
+        fprintf(dest, "const uint8_t DegrFF[NUM_SHORT_FINITE_FIELDS+1] = {\n");
         fprintf(dest, " %3d,", 0);
         for (i = 0, j = 1; i <= MAX_FF; i++) {
             if (is_ff[i]) {
@@ -109,7 +109,7 @@ void emit_code(FILE * dest, int header)
             fprintf(dest, "\n");
         fprintf(dest, "};\n");
         fprintf(dest, "\n");
-        fprintf(dest, "const UInt4 CharFF[NUM_SHORT_FINITE_FIELDS+1] = {\n");
+        fprintf(dest, "const uint32_t CharFF[NUM_SHORT_FINITE_FIELDS+1] = {\n");
         fprintf(dest, " %9d,", 0);
         for (i = 0, j = 1; i <= MAX_FF; i++) {
             if (is_ff[i]) {
@@ -124,7 +124,7 @@ void emit_code(FILE * dest, int header)
             fprintf(dest, "\n");
         fprintf(dest, "};\n");
         fprintf(dest, "\n");
-        fprintf(dest, "const UInt4 SizeFF[NUM_SHORT_FINITE_FIELDS+1] = {\n");
+        fprintf(dest, "const uint32_t SizeFF[NUM_SHORT_FINITE_FIELDS+1] = {\n");
         fprintf(dest, " %9d,", 0);
         for (i = 0, j = 1; i <= MAX_FF; i++) {
             if (is_ff[i]) {
diff --git a/src/extra/compiled.h b/src/extra/compiled.h
new file mode 100644
index 0000000000..342d79ecf4
--- /dev/null
+++ b/src/extra/compiled.h
@@ -0,0 +1,20 @@
+/****************************************************************************
+**
+**  This file is part of GAP, a system for computational discrete algebra.
+**
+**  Copyright of GAP belongs to its developers, whose names are too numerous
+**  to list here. Please refer to the COPYRIGHT file for details.
+**
+**  SPDX-License-Identifier: GPL-2.0-or-later
+**
+**  This header is provided for backwards compatibility with GAP kernel
+**  extensions that are not yet using the `gap_all.h` header (available since
+**  GAP 4.12). Most of these used `compiled.h` instead.
+*/
+
+#ifndef GAP_EXTRA_COMPILED_H
+#define GAP_EXTRA_COMPILED_H
+
+#include "../compiled.h"
+
+#endif // GAP_EXTRA_COMPILED_H
diff --git a/src/extra/gap_all.h b/src/extra/gap_all.h
new file mode 100644
index 0000000000..4c8401ddb0
--- /dev/null
+++ b/src/extra/gap_all.h
@@ -0,0 +1,19 @@
+/****************************************************************************
+**
+**  This file is part of GAP, a system for computational discrete algebra.
+**
+**  Copyright of GAP belongs to its developers, whose names are too numerous
+**  to list here. Please refer to the COPYRIGHT file for details.
+**
+**  SPDX-License-Identifier: GPL-2.0-or-later
+**
+**  This header includes most of the other GAP headers, and is meant to be
+**  included by GAP kernel extensions.
+*/
+
+#ifndef GAP_EXTRA_GAP_ALL_H
+#define GAP_EXTRA_GAP_ALL_H
+
+#include "../gap_all.h"
+
+#endif // GAP_EXTRA_GAP_ALL_H
diff --git a/src/extra/libgap-api.h b/src/extra/libgap-api.h
new file mode 100644
index 0000000000..9c8358bfb2
--- /dev/null
+++ b/src/extra/libgap-api.h
@@ -0,0 +1,18 @@
+/****************************************************************************
+**
+**  This file is part of GAP, a system for computational discrete algebra.
+**
+**  Copyright of GAP belongs to its developers, whose names are too numerous
+**  to list here. Please refer to the COPYRIGHT file for details.
+**
+**  SPDX-License-Identifier: GPL-2.0-or-later
+**
+**  This header includes LibGAP API, the API for using GAP as shared library.
+*/
+
+#ifndef GAP_EXTRA_LIBGAP_API_H
+#define GAP_EXTRA_LIBGAP_API_H
+
+#include "../libgap-api.h"
+
+#endif // GAP_EXTRA_LIBGAP_API_H
diff --git a/src/hpc/aobjects.c b/src/hpc/aobjects.c
index abb467c9fa..0186e85380 100644
--- a/src/hpc/aobjects.c
+++ b/src/hpc/aobjects.c
@@ -10,27 +10,27 @@
 **  This file contains the GAP interface for thread primitives.
 */
 
-#include "hpc/aobjects.h"
-
-#include "hpc/guards.h"
-#include "hpc/thread.h"
-#include "hpc/traverse.h"
-
-#include "ariths.h"
-#include "bool.h"
-#include "calls.h"
-#include "error.h"
-#include "fibhash.h"
-#include "gaputils.h"
-#include "gvars.h"
-#include "io.h"
-#include "lists.h"
-#include "modules.h"
-#include "objects.h"
-#include "plist.h"
-#include "precord.h"
-#include "records.h"
-#include "stringobj.h"
+#include "aobjects.h"
+
+#include "guards.h"
+#include "thread.h"
+#include "traverse.h"
+
+#include "../ariths.h"
+#include "../bool.h"
+#include "../calls.h"
+#include "../error.h"
+#include "../fibhash.h"
+#include "../gaputils.h"
+#include "../gvars.h"
+#include "../io.h"
+#include "../lists.h"
+#include "../modules.h"
+#include "../objects.h"
+#include "../plist.h"
+#include "../precord.h"
+#include "../records.h"
+#include "../stringobj.h"
 
 #include <stdlib.h>     // for labs
 
diff --git a/src/hpc/aobjects.h b/src/hpc/aobjects.h
index c5516b5486..0938f12c9a 100644
--- a/src/hpc/aobjects.h
+++ b/src/hpc/aobjects.h
@@ -11,8 +11,8 @@
 #ifndef GAP_AOBJECTS_H
 #define GAP_AOBJECTS_H
 
-#include "objects.h"
-#include "hpc/atomic.h"
+#include "../objects.h"
+#include "atomic.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
diff --git a/src/hpc/atomic.h b/src/hpc/atomic.h
index dcb96979e0..00d2c8b113 100644
--- a/src/hpc/atomic.h
+++ b/src/hpc/atomic.h
@@ -11,7 +11,7 @@
 #ifndef GAP_ATOMIC_H
 #define GAP_ATOMIC_H
 
-#include "common.h"
+#include "../common.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
diff --git a/src/hpc/cpu.c b/src/hpc/cpu.c
index e28f8f3b12..c99bb9cb96 100644
--- a/src/hpc/cpu.c
+++ b/src/hpc/cpu.c
@@ -8,7 +8,7 @@
 **  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
-#include "hpc/cpu.h"
+#include "cpu.h"
 
 #include <unistd.h>
 
diff --git a/src/hpc/cpu.h b/src/hpc/cpu.h
index 8750913306..7cbabd55c8 100644
--- a/src/hpc/cpu.h
+++ b/src/hpc/cpu.h
@@ -11,7 +11,7 @@
 #ifndef GAP_HPC_CPU_H
 #define GAP_HPC_CPU_H
 
-#include "common.h"
+#include "../common.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
diff --git a/src/hpc/guards.h b/src/hpc/guards.h
index 8e04e6a95a..b22572843e 100644
--- a/src/hpc/guards.h
+++ b/src/hpc/guards.h
@@ -11,8 +11,8 @@
 #ifndef GAP_HPC_GUARD_H
 #define GAP_HPC_GUARD_H
 
-#include "hpc/region.h"
-#include "hpc/tls.h"
+#include "region.h"
+#include "tls.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
diff --git a/src/hpc/misc.c b/src/hpc/misc.c
index a7b962adea..29cb8d0629 100644
--- a/src/hpc/misc.c
+++ b/src/hpc/misc.c
@@ -8,7 +8,7 @@
 **  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
-#include "hpc/misc.h"
+#include "misc.h"
 
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/hpc/misc.h b/src/hpc/misc.h
index 124d76e390..8d7388c389 100644
--- a/src/hpc/misc.h
+++ b/src/hpc/misc.h
@@ -11,7 +11,7 @@
 #ifndef GAP_HPC_MISC_H
 #define GAP_HPC_MISC_H
 
-#include "common.h"
+#include "../common.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
diff --git a/src/hpc/region.c b/src/hpc/region.c
index 2838571991..4569c0bb96 100644
--- a/src/hpc/region.c
+++ b/src/hpc/region.c
@@ -8,17 +8,17 @@
 **  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
-#include "hpc/region.h"
+#include "region.h"
 
 #ifdef USE_BOEHM_GC
-#include "boehm_gc.h"
+#include "../boehm_gc.h"
 #endif
-#include "gasman.h"
-#include "objects.h"
+#include "../gasman.h"
+#include "../objects.h"
 
-// #include "hpc/misc.h"
-#include "hpc/thread.h"
-#include "hpc/guards.h"
+// #include "misc.h"
+#include "thread.h"
+#include "guards.h"
 
 
 #include <pthread.h>
diff --git a/src/hpc/region.h b/src/hpc/region.h
index beb4337cda..f5ade0c159 100644
--- a/src/hpc/region.h
+++ b/src/hpc/region.h
@@ -11,13 +11,13 @@
 #ifndef GAP_REGION_H
 #define GAP_REGION_H
 
-#include "common.h"
+#include "../common.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
 #endif
 
-#include "hpc/atomic.h"
+#include "atomic.h"
 
 typedef struct Region Region;
 
diff --git a/src/hpc/serialize.c b/src/hpc/serialize.c
index 4ac2904df9..3dcd730d93 100644
--- a/src/hpc/serialize.c
+++ b/src/hpc/serialize.c
@@ -8,22 +8,22 @@
 **  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
-#include "hpc/serialize.h"
-
-#include "bool.h"
-#include "calls.h"
-#include "error.h"
-#include "gvars.h"
-#include "modules.h"
-#include "objset.h"
-#include "plist.h"
-#include "precord.h"
-#include "rational.h"
-#include "records.h"
-#include "stringobj.h"
-#include "trycatch.h"
-
-#include "hpc/aobjects.h"
+#include "serialize.h"
+
+#include "../bool.h"
+#include "../calls.h"
+#include "../error.h"
+#include "../gvars.h"
+#include "../modules.h"
+#include "../objset.h"
+#include "../plist.h"
+#include "../precord.h"
+#include "../rational.h"
+#include "../records.h"
+#include "../stringobj.h"
+#include "../trycatch.h"
+
+#include "aobjects.h"
 
 #include <stdio.h>
 
diff --git a/src/hpc/serialize.h b/src/hpc/serialize.h
index 11e77b0222..3ad8d6effd 100644
--- a/src/hpc/serialize.h
+++ b/src/hpc/serialize.h
@@ -11,7 +11,7 @@
 #ifndef GAP_SERIALIZE_H
 #define GAP_SERIALIZE_H
 
-#include "common.h"
+#include "../common.h"
 
 typedef struct SerializerState SerializerState;
 typedef struct DeserializerState DeserializerState;
diff --git a/src/hpc/thread.c b/src/hpc/thread.c
index e63e1ebe4c..420074bf93 100644
--- a/src/hpc/thread.c
+++ b/src/hpc/thread.c
@@ -8,22 +8,22 @@
 **  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
-#include "hpc/thread.h"
-
-#include "code.h"
-#include "error.h"
-#include "fibhash.h"
-#include "gapstate.h"
-#include "gvars.h"
-#include "modules.h"
-#include "plist.h"
-#include "stats.h"
-#include "stringobj.h"
-#include "vars.h"
-
-#include "hpc/guards.h"
-#include "hpc/misc.h"
-#include "hpc/threadapi.h"
+#include "thread.h"
+
+#include "../code.h"
+#include "../error.h"
+#include "../fibhash.h"
+#include "../gapstate.h"
+#include "../gvars.h"
+#include "../modules.h"
+#include "../plist.h"
+#include "../stats.h"
+#include "../stringobj.h"
+#include "../vars.h"
+
+#include "guards.h"
+#include "misc.h"
+#include "threadapi.h"
 
 #include <errno.h>
 #include <pthread.h>
diff --git a/src/hpc/thread.h b/src/hpc/thread.h
index d5b5007ba3..1b0b39b2c1 100644
--- a/src/hpc/thread.h
+++ b/src/hpc/thread.h
@@ -11,7 +11,7 @@
 #ifndef GAP_THREAD_H
 #define GAP_THREAD_H
 
-#include "common.h"
+#include "../common.h"
 
 #if !defined(HPCGAP)
 
@@ -26,8 +26,8 @@
 
 #else
 
-#include "hpc/tlsconfig.h"
-#include "hpc/region.h"
+#include "tlsconfig.h"
+#include "region.h"
 
 // Maximum number of threads excluding the main thread
 #define MAX_THREADS 1023
diff --git a/src/hpc/threadapi.c b/src/hpc/threadapi.c
index 9ff14e2591..0a11e5e1cc 100644
--- a/src/hpc/threadapi.c
+++ b/src/hpc/threadapi.c
@@ -10,34 +10,34 @@
 **  This file contains the GAP interface for thread primitives.
 */
 
-#include "hpc/threadapi.h"
-
-#include "bool.h"
-#include "calls.h"
-#include "code.h"
-#include "error.h"
-#include "funcs.h"
-#include "gvars.h"
-#include "io.h"
-#include "lists.h"
-#include "modules.h"
-#include "objects.h"
-#include "plist.h"
-#include "precord.h"
-#include "read.h"
-#include "records.h"
-#include "set.h"
-#include "stats.h"
-#include "stringobj.h"
-#include "trycatch.h"
-#include "vars.h"
-
-#include "hpc/guards.h"
-#include "hpc/misc.h"
-#include "hpc/region.h"
-#include "hpc/thread.h"
-#include "hpc/tls.h"
-#include "hpc/traverse.h"
+#include "threadapi.h"
+
+#include "../bool.h"
+#include "../calls.h"
+#include "../code.h"
+#include "../error.h"
+#include "../funcs.h"
+#include "../gvars.h"
+#include "../io.h"
+#include "../lists.h"
+#include "../modules.h"
+#include "../objects.h"
+#include "../plist.h"
+#include "../precord.h"
+#include "../read.h"
+#include "../records.h"
+#include "../set.h"
+#include "../stats.h"
+#include "../stringobj.h"
+#include "../trycatch.h"
+#include "../vars.h"
+
+#include "guards.h"
+#include "misc.h"
+#include "region.h"
+#include "thread.h"
+#include "tls.h"
+#include "traverse.h"
 
 #include <signal.h>
 #include <stdio.h>
diff --git a/src/hpc/threadapi.h b/src/hpc/threadapi.h
index 5e064f03cd..5f136ba94d 100644
--- a/src/hpc/threadapi.h
+++ b/src/hpc/threadapi.h
@@ -11,9 +11,9 @@
 #ifndef GAP_THREADAPI_H
 #define GAP_THREADAPI_H
 
-#include "objects.h"
+#include "../objects.h"
 
-#include "gvars.h"
+#include "../gvars.h"
 
 #include <pthread.h>
 
diff --git a/src/hpc/tls.c b/src/hpc/tls.c
index 2f831f6ef2..49e621a436 100644
--- a/src/hpc/tls.c
+++ b/src/hpc/tls.c
@@ -8,8 +8,8 @@
 **  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
-#include "gapstate.h"
-#include "hpc/thread.h"
+#include "../gapstate.h"
+#include "thread.h"
 
 #include <string.h>
 
diff --git a/src/hpc/tls.h b/src/hpc/tls.h
index 80ee594c81..113264c576 100644
--- a/src/hpc/tls.h
+++ b/src/hpc/tls.h
@@ -11,7 +11,7 @@
 #ifndef GAP_TLS_H
 #define GAP_TLS_H
 
-#include "system.h"
+#include "../system.h"
 
 #if !defined(HPCGAP)
 #error This header is only meant to be used with HPC-GAP
@@ -60,7 +60,7 @@
 // assembly code for pthread_getspecific() is implemented in a way
 // consistent with such code.
 
-#include "hpc/tlsconfig.h"
+#include "tlsconfig.h"
 
 #include <setjmp.h>
 
diff --git a/src/hpc/tlsconfig.h b/src/hpc/tlsconfig.h
index d2b6fad6ee..7c8caed57a 100644
--- a/src/hpc/tlsconfig.h
+++ b/src/hpc/tlsconfig.h
@@ -11,7 +11,7 @@
 #ifndef GAP_TLSCONFIG_H
 #define GAP_TLSCONFIG_H
 
-#include "common.h"
+#include "../common.h"
 
 #if !defined(HPCGAP)
 #error This header is only meant to be used with HPC-GAP
diff --git a/src/hpc/traverse.c b/src/hpc/traverse.c
index 9a3900b28d..864ef5a13b 100644
--- a/src/hpc/traverse.c
+++ b/src/hpc/traverse.c
@@ -11,17 +11,17 @@
 /*
  * Functionality to traverse nested object structures.
  */
-#include "hpc/traverse.h"
+#include "traverse.h"
 
-#include "bool.h"
-#include "error.h"
-#include "fibhash.h"
-#include "gaputils.h"
-#include "modules.h"
-#include "plist.h"
+#include "../bool.h"
+#include "../error.h"
+#include "../fibhash.h"
+#include "../gaputils.h"
+#include "../modules.h"
+#include "../plist.h"
 
-#include "hpc/guards.h"
-#include "hpc/thread.h"
+#include "guards.h"
+#include "thread.h"
 
 #ifndef WARD_ENABLED
 
diff --git a/src/hpc/traverse.h b/src/hpc/traverse.h
index e75dac0b8c..5b5989f033 100644
--- a/src/hpc/traverse.h
+++ b/src/hpc/traverse.h
@@ -11,7 +11,7 @@
 #ifndef GAP_TRAVERSE_H
 #define GAP_TRAVERSE_H
 
-#include "common.h"
+#include "../common.h"
 
 typedef struct TraversalState TraversalState;
 
diff --git a/src/version.h.in b/src/version.h.in
index ced22cc7b7..1a8f835589 100644
--- a/src/version.h.in
+++ b/src/version.h.in
@@ -13,9 +13,6 @@
 #ifndef GAP_VERSION_H
 #define GAP_VERSION_H
 
-#include "common.h"
-
-
 /****************************************************************************
 **
 **  GAP_KERNEL_MAJOR_VERSION
diff --git a/tst/testkernel/dstruct.c b/tst/testkernel/dstruct.c
index d219dd3b1b..0da28f7d19 100644
--- a/tst/testkernel/dstruct.c
+++ b/tst/testkernel/dstruct.c
@@ -15,7 +15,7 @@ static int int_cmp(int a, int b)
 #define ELEM_TYPE int
 #define COMPARE int_cmp
 
-#include "baltree.h"
+#include "gap/baltree.h"
 
 void ShowTree(intTree * btree)
 {
@@ -84,7 +84,7 @@ void TestScapegoatTrees(void)
 #define ELEM_TYPE int
 #define COMPARE int_cmp
 
-#include "dynarray.h"
+#include "gap/dynarray.h"
 
 void ShowArray(intArray * arr)
 {
diff --git a/tst/testlibgap/api.c b/tst/testlibgap/api.c
index ab232cf4ca..f2f6cc81db 100644
--- a/tst/testlibgap/api.c
+++ b/tst/testlibgap/api.c
@@ -11,7 +11,6 @@
  */
 
 #include "common.h"
-#include "intobj.h"
 
 #include <string.h>
 
@@ -100,7 +99,7 @@ void matrices(void)
     Obj mat, val, row, ret;
 
     mat = GAP_NewPlist(1);
-    val = INTOBJ_INT(42);
+    val = GAP_NewObjIntFromInt(42);
 
     assert(!GAP_IsMatrixOrMatrixObj(mat));   // empty list, not yet a matrix
     assert(!GAP_IsMatrixObj(mat));
@@ -113,8 +112,8 @@ void matrices(void)
     assert(!GAP_IsMatrix(val));
 
     row = GAP_NewPlist(2);
-    GAP_AssList(row, 1, INTOBJ_INT(1));
-    GAP_AssList(row, 2, INTOBJ_INT(2));
+    GAP_AssList(row, 1, GAP_NewObjIntFromInt(1));
+    GAP_AssList(row, 2, GAP_NewObjIntFromInt(2));
     GAP_AssList(mat, 1, row);
     assert(!GAP_IsMatrixOrMatrixObj(row));
     assert(!GAP_IsMatrixObj(row));
diff --git a/tst/testlibgap/trycatch.c b/tst/testlibgap/trycatch.c
index 55dd1e781d..393bd298f7 100644
--- a/tst/testlibgap/trycatch.c
+++ b/tst/testlibgap/trycatch.c
@@ -1,7 +1,7 @@
 /*
  * Small program to test libgap linkability and basic working
  */
-#include "trycatch.h"
+#include "gap_all.h"
 #include "common.h"
 
 static int level = 0;