diff --git a/libsgp4/CMakeLists.txt b/libsgp4/CMakeLists.txt
index f306933..b816645 100644
--- a/libsgp4/CMakeLists.txt
+++ b/libsgp4/CMakeLists.txt
@@ -1,20 +1,20 @@
 set(SRCS
-    CoordGeodetic.cpp
-    CoordTopocentric.cpp
-    DateTime.cpp
-    DecayedException.cpp
-    Eci.cpp
-    Globals.cpp
-    Observer.cpp
-    OrbitalElements.cpp
-    SGP4.cpp
-    SatelliteException.cpp
-    SolarPosition.cpp
-    TimeSpan.cpp
-    Tle.cpp
-    TleException.cpp
-    Util.cpp
-    Vector.cpp)
+    CoordGeodetic.cc
+    CoordTopocentric.cc
+    DateTime.cc
+    DecayedException.cc
+    Eci.cc
+    Globals.cc
+    Observer.cc
+    OrbitalElements.cc
+    SGP4.cc
+    SatelliteException.cc
+    SolarPosition.cc
+    TimeSpan.cc
+    Tle.cc
+    TleException.cc
+    Util.cc
+    Vector.cc)
 
   set(INCS
      CoordGeodetic.h
diff --git a/libsgp4/CoordGeodetic.cpp b/libsgp4/CoordGeodetic.cc
similarity index 100%
rename from libsgp4/CoordGeodetic.cpp
rename to libsgp4/CoordGeodetic.cc
diff --git a/libsgp4/CoordTopocentric.cpp b/libsgp4/CoordTopocentric.cc
similarity index 100%
rename from libsgp4/CoordTopocentric.cpp
rename to libsgp4/CoordTopocentric.cc
diff --git a/libsgp4/DateTime.cpp b/libsgp4/DateTime.cc
similarity index 100%
rename from libsgp4/DateTime.cpp
rename to libsgp4/DateTime.cc
diff --git a/libsgp4/DecayedException.cpp b/libsgp4/DecayedException.cc
similarity index 100%
rename from libsgp4/DecayedException.cpp
rename to libsgp4/DecayedException.cc
diff --git a/libsgp4/Eci.cpp b/libsgp4/Eci.cc
similarity index 100%
rename from libsgp4/Eci.cpp
rename to libsgp4/Eci.cc
diff --git a/libsgp4/Globals.cpp b/libsgp4/Globals.cc
similarity index 100%
rename from libsgp4/Globals.cpp
rename to libsgp4/Globals.cc
diff --git a/libsgp4/Observer.cpp b/libsgp4/Observer.cc
similarity index 100%
rename from libsgp4/Observer.cpp
rename to libsgp4/Observer.cc
diff --git a/libsgp4/OrbitalElements.cpp b/libsgp4/OrbitalElements.cc
similarity index 100%
rename from libsgp4/OrbitalElements.cpp
rename to libsgp4/OrbitalElements.cc
diff --git a/libsgp4/SGP4.cpp b/libsgp4/SGP4.cc
similarity index 100%
rename from libsgp4/SGP4.cpp
rename to libsgp4/SGP4.cc
diff --git a/libsgp4/SatelliteException.cpp b/libsgp4/SatelliteException.cc
similarity index 100%
rename from libsgp4/SatelliteException.cpp
rename to libsgp4/SatelliteException.cc
diff --git a/libsgp4/SolarPosition.cpp b/libsgp4/SolarPosition.cc
similarity index 100%
rename from libsgp4/SolarPosition.cpp
rename to libsgp4/SolarPosition.cc
diff --git a/libsgp4/TimeSpan.cpp b/libsgp4/TimeSpan.cc
similarity index 100%
rename from libsgp4/TimeSpan.cpp
rename to libsgp4/TimeSpan.cc
diff --git a/libsgp4/Tle.cpp b/libsgp4/Tle.cc
similarity index 100%
rename from libsgp4/Tle.cpp
rename to libsgp4/Tle.cc
diff --git a/libsgp4/TleException.cpp b/libsgp4/TleException.cc
similarity index 100%
rename from libsgp4/TleException.cpp
rename to libsgp4/TleException.cc
diff --git a/libsgp4/Util.cpp b/libsgp4/Util.cc
similarity index 100%
rename from libsgp4/Util.cpp
rename to libsgp4/Util.cc
diff --git a/libsgp4/Vector.cpp b/libsgp4/Vector.cc
similarity index 100%
rename from libsgp4/Vector.cpp
rename to libsgp4/Vector.cc
diff --git a/passpredict/CMakeLists.txt b/passpredict/CMakeLists.txt
index c0f0b85..5d6cf00 100644
--- a/passpredict/CMakeLists.txt
+++ b/passpredict/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(SRCS
-    passpredict.cpp)
+    passpredict.cc)
 
 add_executable(passpredict
     ${SRCS})
diff --git a/passpredict/passpredict.cpp b/passpredict/passpredict.cc
similarity index 100%
rename from passpredict/passpredict.cpp
rename to passpredict/passpredict.cc
diff --git a/runtest/CMakeLists.txt b/runtest/CMakeLists.txt
index c446be3..7a1cf26 100644
--- a/runtest/CMakeLists.txt
+++ b/runtest/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(SRCS
-    runtest.cpp)
+    runtest.cc)
 
 add_executable(runtest
     ${SRCS})
diff --git a/runtest/runtest.cpp b/runtest/runtest.cc
similarity index 100%
rename from runtest/runtest.cpp
rename to runtest/runtest.cc
diff --git a/sattrack/CMakeLists.txt b/sattrack/CMakeLists.txt
index c61139f..0664458 100644
--- a/sattrack/CMakeLists.txt
+++ b/sattrack/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(SRCS
-    sattrack.cpp)
+    sattrack.cc)
 
 add_executable(sattrack
     ${SRCS})
diff --git a/sattrack/sattrack.cpp b/sattrack/sattrack.cc
similarity index 100%
rename from sattrack/sattrack.cpp
rename to sattrack/sattrack.cc