diff --git a/docs/cpp-api/Doxyfile b/docs/cpp-api/Doxyfile
index 27071686b4..ac7452c780 100644
--- a/docs/cpp-api/Doxyfile
+++ b/docs/cpp-api/Doxyfile
@@ -48,7 +48,7 @@ PROJECT_NAME           = IfcOpenShell
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         =
+PROJECT_NUMBER         = $(PROJECT_NUMBER)
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
@@ -68,7 +68,7 @@ PROJECT_LOGO           =
 # entered, it will be relative to the location where doxygen was started. If
 # left blank the current directory will be used.
 
-OUTPUT_DIRECTORY       = ./output/doxygen
+OUTPUT_DIRECTORY       = ./output
 
 # If the CREATE_SUBDIRS tag is set to YES then doxygen will create up to 4096
 # sub-directories (in 2 levels) under the output directory of each output format
@@ -483,7 +483,7 @@ TYPEDEF_HIDES_STRUCT   = NO
 # the optimal cache size from a speed point of view.
 # Minimum value: 0, maximum value: 9, default value: 0.
 
-LOOKUP_CACHE_SIZE      = 3
+LOOKUP_CACHE_SIZE      = 4
 
 # The NUM_PROC_THREADS specifies the number of threads doxygen is allowed to use
 # during processing. When set to 0 doxygen will based this on the number of
@@ -496,7 +496,7 @@ LOOKUP_CACHE_SIZE      = 3
 # DOT_NUM_THREADS setting.
 # Minimum value: 0, maximum value: 32, default value: 1.
 
-NUM_PROC_THREADS       = 1
+NUM_PROC_THREADS       = 0
 
 # If the TIMESTAMP tag is set different from NO then each generated page will
 # contain the date or date and time when the page was generated. Setting this to
@@ -943,10 +943,10 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = ../src/ifcgeom \
-                         ../src/ifcgeom_schema_agnostic \
-                         ../src/ifcparse \
-                         ../src/serializers \
+INPUT                  = ../../src/ifcgeom \
+                         ../../src/ifcgeom_schema_agnostic \
+                         ../../src/ifcparse \
+                         ../../src/serializers \
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses