diff --git a/repos/gems/run/depot_autopilot.run b/repos/gems/run/depot_autopilot.run
index bd49ead80b..060a31fe4e 100644
--- a/repos/gems/run/depot_autopilot.run
+++ b/repos/gems/run/depot_autopilot.run
@@ -456,7 +456,7 @@ proc prepare_to_run_genode { } {
 	set serial_id -1
 	set timeout 40
 
-	append qemu_args "-m 768 -nographic "
+	append qemu_args "-m 800 -nographic "
 }
 
 
diff --git a/repos/gems/run/driver_manager.run b/repos/gems/run/driver_manager.run
index de875dd367..8efad0b9a0 100644
--- a/repos/gems/run/driver_manager.run
+++ b/repos/gems/run/driver_manager.run
@@ -164,7 +164,6 @@ if {[have_include "power_on/qemu"]} {
 #
 # Qemu opts for supplying hdd_disk.raw as AHCI disk
 #
-append qemu_args " -m 128 "
 append qemu_args " -nographic "
 append qemu_args " -device ahci,id=ahci "
 append qemu_args " -drive id=hdd,file=bin/hdd_disk.raw,format=raw,if=none -device ide-hd,drive=hdd,bus=ahci.1 "
diff --git a/repos/gems/run/sculpt_test.run b/repos/gems/run/sculpt_test.run
index 7e58e2e4d3..b3e3268516 100644
--- a/repos/gems/run/sculpt_test.run
+++ b/repos/gems/run/sculpt_test.run
@@ -4,7 +4,7 @@ source ${genode_dir}/repos/gems/run/sculpt.run
 
 # enable Qemu networking, usable via the nic_drv
 append_qemu_nic_args
-append qemu_args " -m 768 "
+append qemu_args " -m 1024 "
 
 # attach small SATA disk to Qemu to experiment with file-system access
 set disk_image "bin/sculpt-ahci.raw"
diff --git a/repos/gems/run/ssh_terminal.run b/repos/gems/run/ssh_terminal.run
index 2679461077..6d32e99195 100644
--- a/repos/gems/run/ssh_terminal.run
+++ b/repos/gems/run/ssh_terminal.run
@@ -240,7 +240,7 @@ build_boot_image $boot_modules
 # Execute test
 #
 
-append qemu_args     " -m 512 -nographic "
+append qemu_args     " -nographic "
 append_qemu_nic_args "hostfwd=tcp::5555-:22"
 
 set lxip_match_string "ipaddr=(\[0-9\]+\.\[0-9\]+\.\[0-9\]+\.\[0-9\]+).*\n"
diff --git a/repos/libports/run/mupdf.run b/repos/libports/run/mupdf.run
index 7a385922e4..32be5c1764 100644
--- a/repos/libports/run/mupdf.run
+++ b/repos/libports/run/mupdf.run
@@ -128,7 +128,7 @@ append boot_modules {
 
 build_boot_image $boot_modules
 
-append qemu_args " -m 768"
+append qemu_args " -m 800"
 
 run_genode_until forever
 
diff --git a/repos/os/run/block_request_stream.run b/repos/os/run/block_request_stream.run
index 673de36b7d..a8d0d0d4a2 100644
--- a/repos/os/run/block_request_stream.run
+++ b/repos/os/run/block_request_stream.run
@@ -62,6 +62,6 @@ install_config {
 build_boot_image { core init timer block_tester test-block_request_stream ld.lib.so }
 
 
-append qemu_args " -nographic -m 512 "
+append qemu_args " -nographic "
 
 run_genode_until {.*child "block_tester" exited with exit value 0.*\n} 360
diff --git a/repos/os/run/block_tester.run b/repos/os/run/block_tester.run
index a8a6defb8c..5a9a401491 100644
--- a/repos/os/run/block_tester.run
+++ b/repos/os/run/block_tester.run
@@ -355,7 +355,7 @@ append_platform_drv_boot_modules
 
 build_boot_image $boot_modules
 
-append qemu_args " -nographic -m 512 -nographic"
+append qemu_args " -nographic -nographic"
 append qemu_args " -drive id=disk,file=bin/block0.raw,format=raw,if=none \
                    -drive id=disk2,file=bin/block1.raw,format=raw,if=none \
                    -device ahci,id=ahci -device ide-hd,drive=disk,bus=ahci.0 \
diff --git a/repos/os/run/nvme.run b/repos/os/run/nvme.run
index 3029789348..a3a7aa0f86 100644
--- a/repos/os/run/nvme.run
+++ b/repos/os/run/nvme.run
@@ -194,7 +194,7 @@ append_platform_drv_boot_modules
 
 build_boot_image $boot_modules
 
-append qemu_args " -nographic -m 512 "
+append qemu_args " -nographic "
 append qemu_args " -drive id=nvme0,file=bin/nvme.raw,format=raw,if=none "
 append qemu_args " -device nvme,drive=nvme0,serial=fnord,id=nvme0n1 "
 
diff --git a/repos/ports/run/tool_chain_auto.run b/repos/ports/run/tool_chain_auto.run
index 4c2d662b84..7dac23e4eb 100644
--- a/repos/ports/run/tool_chain_auto.run
+++ b/repos/ports/run/tool_chain_auto.run
@@ -251,7 +251,7 @@ lappend boot_modules libc.lib.so vfs.lib.so vfs_pipe.lib.so vfs
 build_boot_image $boot_modules
 
 
-append qemu_args " -nographic -m 768 "
+append qemu_args " -nographic -m 800 "
 
 # wait until Noux started
 run_genode_until {.*\[init -> vfs\] creating build directory\.\.\..*\n} $boot_timeout
diff --git a/repos/ports/run/virtualbox.run b/repos/ports/run/virtualbox.run
index c963e817da..bc04c5c1a4 100644
--- a/repos/ports/run/virtualbox.run
+++ b/repos/ports/run/virtualbox.run
@@ -309,7 +309,7 @@ if {[have_include "power_on/qemu"]} {
 	if {[expr $use_gui]} {
 		append qemu_args " -m 2048 "
 	} else {
-		append qemu_args " -m 768 "
+		append qemu_args " -m 1024 "
 	}
 
 	append qemu_args " -cpu phenom "
diff --git a/tool/run/power_on/qemu b/tool/run/power_on/qemu
index 880c5f21e9..1d328badad 100644
--- a/tool/run/power_on/qemu
+++ b/tool/run/power_on/qemu
@@ -121,14 +121,28 @@ proc run_power_on { } {
 
 	# on x86, we support booting via pxe or iso/disk image
 	if {[have_board pc]} {
-		if {![regexp -- {-m} $qemu_args dummy]} {
-			if {[have_spec okl4]} {
-				# okl4 system integration specifies RAM from 32 to 800 MiB
-				append qemu_args " -m 800 "
-			} else {
-				append qemu_args " -m 512 "
+		if {[have_spec okl4]} {
+			# okl4 system integration specifies RAM from 32 to 800 MiB
+			set qemu_ram 800
+		} else {
+			set qemu_ram 512
+		}
+
+		if {[regexp -- {-m} $qemu_args dummy]} {
+			set qemu_ram [regexp -inline {\-m.[0-9]+} $qemu_args]
+			set qemu_ram [regexp -inline {[0-9]+} $qemu_ram]
+		}
+
+		if {[have_spec okl4]} {
+			if {$qemu_ram < 800} {
+				puts "Configured memory ($qemu_ram) for OKL4 on Qemu must be at least 800M\n"
+				exit 1
 			}
 		}
+
+		append qemu_args " -m $qemu_ram "
+
+
 		if {[have_include "load/tftp"]} {
 			append qemu_args " -boot n -tftp [run_dir] -bootp boot/pulsar -no-reboot -no-shutdown "
 		} else {