diff --git a/src/build/libroot/Jamfile b/src/build/libroot/Jamfile
index e1ebd9d509..0104f25cf3 100644
--- a/src/build/libroot/Jamfile
+++ b/src/build/libroot/Jamfile
@@ -67,7 +67,7 @@ local librootSources =
 	driver_settings.cpp
 
 	$(strlSources)
-	strnlen.c
+	strnlen.cpp
 
 	KMessage.cpp
 ;
@@ -93,7 +93,7 @@ BuildPlatformStaticLibraryPIC libroot_build_function_remapper.a :
 
 SEARCH on [ FGristFiles driver_settings.cpp ]
 	= [ FDirName $(HAIKU_TOP) src system libroot os ] ;
-SEARCH on [ FGristFiles $(strlSources) strnlen.c ]
+SEARCH on [ FGristFiles $(strlSources) strnlen.cpp ]
 	= [ FDirName $(HAIKU_TOP) src system libroot posix string ] ;
 SEARCH on [ FGristFiles KMessage.cpp ]
     = [ FDirName $(HAIKU_TOP) src system kernel messaging ] ;
diff --git a/src/system/kernel/lib/Jamfile b/src/system/kernel/lib/Jamfile
index 77e0958c8b..5d4cba6850 100644
--- a/src/system/kernel/lib/Jamfile
+++ b/src/system/kernel/lib/Jamfile
@@ -109,12 +109,12 @@ KernelMergeObject kernel_lib_posix.o :
 	strerror.c
 	strlcat.c
 	strlcpy.c
-	strlen.c
+	strlen.cpp
 	strncat.c
 	strncmp.c
 	strncpy.c
 	strndup.cpp
-	strnlen.c
+	strnlen.cpp
 	strpbrk.c
 	strrchr.c
 	strspn.c
diff --git a/src/system/libroot/posix/string/Jamfile b/src/system/libroot/posix/string/Jamfile
index 8fdbe7b538..a844ff0f31 100644
--- a/src/system/libroot/posix/string/Jamfile
+++ b/src/system/libroot/posix/string/Jamfile
@@ -33,7 +33,7 @@ MergeObject posix_string.o :
 	strncmp.c
 	strncpy.c
 	strndup.cpp
-	strnlen.c
+	strnlen.cpp
 	strpbrk.c
 	strrchr.c
 	strspn.c
diff --git a/src/system/libroot/posix/string/strlen.c b/src/system/libroot/posix/string/strlen.cpp
similarity index 100%
rename from src/system/libroot/posix/string/strlen.c
rename to src/system/libroot/posix/string/strlen.cpp
diff --git a/src/system/libroot/posix/string/strnlen.c b/src/system/libroot/posix/string/strnlen.cpp
similarity index 100%
rename from src/system/libroot/posix/string/strnlen.c
rename to src/system/libroot/posix/string/strnlen.cpp