diff --git a/boards/sim/sim/sim/configs/cxxtest/Make.defs b/boards/sim/sim/sim/configs/cxxtest/Make.defs
index 633eed8e9e..dfab86026c 100644
--- a/boards/sim/sim/sim/configs/cxxtest/Make.defs
+++ b/boards/sim/sim/sim/configs/cxxtest/Make.defs
@@ -86,6 +86,18 @@ else
   LDMODULEFLAGS += -T $(TOPDIR)/libs/libc/modlib/gnu-elf.ld
 endif
 
+# NuttX modules are ELF binaries.
+# Non-ELF platforms like macOS need to use a separate ELF toolchain.
+ifeq ($(CONFIG_HOST_MACOS),y)
+  # eg. brew install x86_64-elf-gcc
+  MODULECC = x86_64-elf-gcc
+  MODULELD = x86_64-elf-ld
+  # It seems macOS/x86_64 loads the program text around 00000001_xxxxxxxx.
+  # The gcc default (-mcmodel=small) would produce out-of-range 32-bit
+  # relocations.
+  CMODULEFLAGS += -mcmodel=large
+endif
+
 # ELF module definitions
 
 CELFFLAGS = $(CFLAGS)
diff --git a/boards/sim/sim/sim/configs/nsh2/Make.defs b/boards/sim/sim/sim/configs/nsh2/Make.defs
index 21e67fc703..4b187580f3 100644
--- a/boards/sim/sim/sim/configs/nsh2/Make.defs
+++ b/boards/sim/sim/sim/configs/nsh2/Make.defs
@@ -82,6 +82,18 @@ else
   LDMODULEFLAGS += -T $(TOPDIR)/libs/libc/modlib/gnu-elf.ld
 endif
 
+# NuttX modules are ELF binaries.
+# Non-ELF platforms like macOS need to use a separate ELF toolchain.
+ifeq ($(CONFIG_HOST_MACOS),y)
+  # eg. brew install x86_64-elf-gcc
+  MODULECC = x86_64-elf-gcc
+  MODULELD = x86_64-elf-ld
+  # It seems macOS/x86_64 loads the program text around 00000001_xxxxxxxx.
+  # The gcc default (-mcmodel=small) would produce out-of-range 32-bit
+  # relocations.
+  CMODULEFLAGS += -mcmodel=large
+endif
+
 # ELF module definitions
 
 CELFFLAGS = $(CFLAGS)
diff --git a/boards/sim/sim/sim/scripts/Make.defs b/boards/sim/sim/sim/scripts/Make.defs
index c49735ee86..c338812976 100644
--- a/boards/sim/sim/sim/scripts/Make.defs
+++ b/boards/sim/sim/sim/scripts/Make.defs
@@ -88,6 +88,18 @@ else
   LDMODULEFLAGS += -T $(TOPDIR)/libs/libc/modlib/gnu-elf.ld
 endif
 
+# NuttX modules are ELF binaries.
+# Non-ELF platforms like macOS need to use a separate ELF toolchain.
+ifeq ($(CONFIG_HOST_MACOS),y)
+  # eg. brew install x86_64-elf-gcc
+  MODULECC = x86_64-elf-gcc
+  MODULELD = x86_64-elf-ld
+  # It seems macOS/x86_64 loads the program text around 00000001_xxxxxxxx.
+  # The gcc default (-mcmodel=small) would produce out-of-range 32-bit
+  # relocations.
+  CMODULEFLAGS += -mcmodel=large
+endif
+
 # ELF module definitions
 
 CELFFLAGS = $(CFLAGS)