diff --git a/dmd/constfold.c b/dmd/constfold.c
index 5e20f736..34b2c49a 100644
--- a/dmd/constfold.c
+++ b/dmd/constfold.c
@@ -487,6 +487,9 @@ Expression *Mod(Type *type, Expression *e1, Expression *e2)
 	    c = fmodl(e1->toReal(), r2) + fmodl(e1->toImaginary(), r2) * I;
 #elif defined(IN_GCC)
 	    c = complex_t(e1->toReal() % r2, e1->toImaginary() % r2);
+#elif defined(__FreeBSD__) && __FreeBSD_version < 800000
+        // freebsd is kinda messed up. the STABLE branch doesn't support C99's fmodl !?!
+        c = complex_t(fmod(e1->toReal(), r2), fmod(e1->toImaginary(), r2));
 #else
 	    c = complex_t(fmodl(e1->toReal(), r2), fmodl(e1->toImaginary(), r2));
 #endif
@@ -498,6 +501,9 @@ Expression *Mod(Type *type, Expression *e1, Expression *e2)
 	    c = fmodl(e1->toReal(), i2) + fmodl(e1->toImaginary(), i2) * I;
 #elif defined(IN_GCC)
 	    c = complex_t(e1->toReal() % i2, e1->toImaginary() % i2);
+#elif defined(__FreeBSD__) && __FreeBSD_version < 800000
+        // freebsd is kinda messed up. the STABLE branch doesn't support C99's fmodl !?!
+        c = complex_t(fmod(e1->toReal(), i2), fmod(e1->toImaginary(), i2));
 #else
 	    c = complex_t(fmodl(e1->toReal(), i2), fmodl(e1->toImaginary(), i2));
 #endif
diff --git a/dmd/mars.c b/dmd/mars.c
index 84a43210..c4585b23 100644
--- a/dmd/mars.c
+++ b/dmd/mars.c
@@ -330,8 +330,10 @@ int main(int argc, char *argv[])
     global.params.os = OSLinux;
 #elif __APPLE__
     global.params.os = OSMacOSX;
+#elif __FreeBSD__
+    global.params.os = OSFreeBSD;
 #else
-#error
+#error Unsupported OS
 #endif /* linux */
 
     assert(global.params.os != OSinvalid);
@@ -843,6 +845,11 @@ int main(int argc, char *argv[])
 	global.params.tt_os = "-pc-darwin-gnu";
     break;
 
+    case OSFreeBSD:
+    VersionCondition::addPredefinedGlobalIdent("freebsd");
+    VersionCondition::addPredefinedGlobalIdent("Posix");
+    break;
+
     default:
 	assert(false && "Target OS not supported");
     }
diff --git a/dmd/mars.h b/dmd/mars.h
index 008a7c31..219c39c9 100644
--- a/dmd/mars.h
+++ b/dmd/mars.h
@@ -52,7 +52,8 @@ enum OS
     OSinvalid,
     OSLinux,
     OSWindows,
-    OSMacOSX
+    OSMacOSX,
+    OSFreeBSD
 };
 
 // Put command line switches in here
diff --git a/gen/linker.cpp b/gen/linker.cpp
index abc045b1..5176080a 100644
--- a/gen/linker.cpp
+++ b/gen/linker.cpp
@@ -151,15 +151,18 @@ int linkExecutable(const char* argv0)
     }
 
     // default libs
-    if(global.params.os == OSLinux || global.params.os == OSMacOSX)
-    {
-        args.push_back("-lpthread");
+    switch(global.params.os) {
+    case OSLinux:
+    case OSMacOSX:
         args.push_back("-ldl");
+    case OSFreeBSD:
+        args.push_back("-lpthread");
         args.push_back("-lm");
-    }
-    else if (global.params.os == OSWindows)
-    {
+        break;
+
+    case OSWindows:
         // FIXME: I'd assume kernel32 etc
+        break;
     }
 
     // object files
diff --git a/gen/tollvm.cpp b/gen/tollvm.cpp
index fb295428..95df537b 100644
--- a/gen/tollvm.cpp
+++ b/gen/tollvm.cpp
@@ -704,6 +704,12 @@ const LLStructType* DtoMutexType()
         return LLStructType::get(types);
     }
 
+    // FreeBSD
+    else if (global.params.os == OSFreeBSD) {
+        // Just a pointer
+        return LLStructType::get(DtoSize_t(), 0);
+    }
+
     // pthread_fastlock
     std::vector<const LLType*> types2;
     types2.push_back(DtoSize_t());
diff --git a/runtime/internal/critical.c b/runtime/internal/critical.c
index 9bb41143..56231d61 100644
--- a/runtime/internal/critical.c
+++ b/runtime/internal/critical.c
@@ -75,7 +75,7 @@ void _STD_critical_term()
 
 /* ================================= linux ============================ */
 
-#if linux || __APPLE__
+#if linux || __APPLE__ || __FreeBSD__
 
 #include	<stdio.h>
 #include	<stdlib.h>
diff --git a/tests/runtest b/tests/runtest
index c6393789..b749558d 100755
--- a/tests/runtest
+++ b/tests/runtest
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # check for command line arguments
 if [ -z "$1" ] ; then