diff --git a/plat/build.lua b/plat/build.lua
index 017628abe..a6f9e7a59 100644
--- a/plat/build.lua
+++ b/plat/build.lua
@@ -48,6 +48,27 @@ definerule("acklibrary",
 	},
 	function (e)
 		local em = (e.vars.plat or ""):find("^em")
+
+		local commands = {
+			"rm -f %{outs[1]}",
+		}
+		local t = {}
+		local function flush()
+			commands[#commands+1] = 
+				"ACKDIR=$(INSDIR) $(INSDIR)/bin/aal qc %{outs[1]} "..
+					asstring(t)
+			t = {}
+		end
+		for _, target in ipairs(filenamesof(e.srcs)) do
+			t[#t+1] = target
+			if #t == 100 then
+				flush()
+			end
+		end
+		if #t ~= 0 then
+			flush()
+		end
+
 		return clibrary {
 			name = e.name,
 			srcs = e.srcs,
@@ -58,10 +79,7 @@ definerule("acklibrary",
 			},
 			_cfile = ackfile,
 			suffix = em and ".m" or ".o",
-			commands = {
-				"rm -f %{outs[1]}",
-				"ACKDIR=$(INSDIR) $(INSDIR)/bin/aal qc %{outs[1]} %{ins}"
-			}
+			commands = commands
 		}
 	end
 )