diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7b0ca6357de..365d5931bcf 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2018-12-19  Tom de Vries  <tdevries@suse.de>
+
+	* config/nvptx/nvptx.c (PTX_CTA_SIZE): Define.
+
 2018-12-19  Tom de Vries  <tdevries@suse.de>
 
 	* omp-offload.c (oacc_fn_attrib_level): Remove static.
diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index 2a2d638e6d7..f4095ff5f55 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -86,6 +86,11 @@
 #define PTX_WORKER_LENGTH 32
 #define PTX_DEFAULT_RUNTIME_DIM 0 /* Defer to runtime.  */
 
+/* The PTX concept CTA (Concurrent Thread Array) maps on the CUDA concept thread
+   block, which has had a maximum number of threads of 1024 since CUDA version
+   2.x.  */
+#define PTX_CTA_SIZE 1024
+
 /* The various PTX memory areas an object might reside in.  */
 enum nvptx_data_area
 {